Thursday, 6 December 2012

SCIENCE form 4 all topics (nota ringkas)

Method of Scientific Investigation

Scientific investigation method 

  • A scientific method is a series of systematic steps which a scientist practises when conducting an investigation.
  • The steps of a scientific investigation are as follows:
    • Identifying the problem
    • Identifying the variables
    • Making a hypothesis
    • Planning the investigation
    • Carrying out the experiment
    • Collecting and recording data
    • Analysing and interpreting data
    • Making a conclusion 
    • Writing a report
  • Making a hypothesis
    • Making hypothesis is the process of forming a general statement about the relationship between the variable that is manipulated and the responding variable.
    • a hypothesis is also a statement of a scientific concept or principle made as a solution to the problem.
  • Planning investigation
    • then planning of an investigation often involves the following:
      • determining the apparatus and materials
      • determining the procedures
      • determining the observation to be made and measurements
      • determining the correct and safe techniques
      • determining the set of apparatus of control experiments
      • identifying the variables
  • Carrying out the investigation
    • the apparatus, materials and procedures must be handled correctly and safely when carrying out investigations.
    • The variebles must be determined accurately
    • The observations must be made accurately and objectively.
  • Collecting and recording data
    • Data collected by measurement in digits are called quantitative data.
    • Data collected by more observation and do not involve accurate measurements are known as qualitative data.An assessment of the characteristics of an observation is also part of the qualitative data.
    • The data collected can be recorded in the form of:
      • Table
      • Graph
      • Pie chart
      • Diagram
      • Histogram
      • Bar chart
  • Analysing and interpreting data
  • Analysing and interpreting data
  • Making a conclusion
  • Writing a report
A scientist must have scientific attitudes and noble values such asa being curious in stating a problem statement, being honest and accurate in recordibg and validating data, being responsible for the safety of oneself, others and the environment when conducting an experiment, being critical and analytical thinking when proposing a hypothesis and being objective when making a conclusion.

The scientific attitudes and noble values ned to be practised when conducting a scientific investigation to ensure a better understanding and interpretation of a scientific investigation.
A scientist must have scientific attitudes and noble values such asa being curious in stating a problem statement, being honest and accurate in recordibg and validating data, being responsible for the safety of oneself, others and the environment when conducting an experiment, being critical and analytical thinking when proposing a hypothesis and being objective when making a conclusion.

Body Coordination
  • Body coordination is a life process that involves harmonious fuctioning of interrelated organs and parts in the body to produce a coordinated response
  • Two body systems that control and regulate coordination are:
    • The nervous system
    • The endocrine system
  • A stimulus is a detectable change in the internal or external environment.It evokes a response.
  • Response is an action or movement as a result of a stimulus.
  • The nervous system handles fast and short responses which involve the transmission of electrical impulses
 The Human Nervous System
  • The human nervous system can be divided into:
    • The central nervous system (CNS) which consists of the brain and spinal cord.
    • The peripheral nervous system (PNS) which consists of cranial nerves and spinal nerves.

nervous system
  • A neurone is a nerve cell which is the basic functional unit of the nervous system
  • The central nernous system consists of the brain and spinal cord
  • The peripheral nervous system consists of cranial nerves and spinal nerves.
  • The brain is an organ that is the centre of control and coordination in the nervous system
  • The spinal cord controls reflex action
  • The peripheral nervous  system is the network of nerves which connect the central nervous system with other parts of the body.
  • Cranial nerves composed of 12 pairs of nerves which orogonate from the brain and are connected to sense organs in the head and neck, and also to effectors such as the muscles or glands in the body cavity.
  • Spinal nerves are composed of 31 pairs of nerves which originate from spinal cord and are connected to sense organs and effectors in the whole body including hands and legs.
  • A neurone is a nerve cell.It is the basic functional unit of the nervous system
  • The cell body contains many projections
    • Dendrons - projections from the cytoplasm that point outward from the cell body
    • Dendrites - smaller projections that branch from dendrons or axons
    • Axons - another type of projection
  • Dendrans and dendrites receive messages from other cells and trnasmit the message to the cell body
  • Axons conduct messages away from the cell body
  • Some axons in certain neurones are covered by myelin sheath.The sheath breaks up at intervals along the dendrons or axons.This enables impulses to jump from one node to another, shortening the time impulses travel along the surface of the axons or dendrons.
  • Besides this, the meylin sheath is important because:
    • It acts as an electrical insulator
    • it is a source of food for axons and dendrons
    • it also protects axons and dendrons from physical injury.
Types of neurones
  • There are three types of neurones
    • sensory neurones
    • motor neurones
    • interneurones (relay neurones)

Nervous Coordination

Receptors and effectors

  • Any changes which occur inside and outside of the human body are known as stimuli
  • Receptors are sensory cells that detect and receive stimuli and turn them into electrical impulses
  • Effectors are muscles or glands which produce responses due to stimuli.They respond to stimuli by:
    • contraction
    • gland secretion
  • Figure above shows how the human nervous system works.                            
Nerve Impulses
  • are messages conveyed along the nerve in the form of weak electrical pulse
  • An impulse moves only in one direction as shown in figure.

                        Impulses move in one direction

Reflex action

  • A reflex action is a rapid,automatic unlearned response to a stimulus.This action is involuntary and cannot be controlled by the brain
  • A reflex action does not require conscious thought or decision by the brain
  • The components involved in a reflex action are:
    • The receptors
    • The effectors
    • Sensory neurones
    • Relay neurones 
    • Motor neurones
Reflex arc
  • A reflex arc is a sequence of pathways taken by the impulses from receptors to effectors in a reflex action
  • The pathway of impulses in a reflex arc are as follow:

Pathway  of impulses


  • Proprioceptors are sense organs which are connected to sensory neurones.Humans are able to determine the position of their legs, arms, head and other parts, along with the orientation of the body as a whole with this type of receptors
  • Proprioceptors are found in all skeletal muscles, tendons, ligaments and joints.They provide information to the brain regarding adjustment in posture and movement.Therefore, adjusments may be made to maintain body posture or to carry out a particular body movement.
  • Kinaesthesis is the ability to sense the position, location, orientation and movement of the body and its part without looking at ourselves.

The Human Brain and Its Complexity

Structure of the brain

  • The human brain is the most complex organs in the human body.It is also the most complex brain among all mammals.
  • The brain is the centre that contols and coordinates our responses as shown in above

  • The human brain has an external layer which is white in colour.
    • The grey-coloured layer is made up of closely packed neurone cell bodies which form the grey matter of the brain
    • The white-coloured layer is made up of nerve fibres which form the white matter of the brain
  • The human brain can be divided into three main parts:
    • Cerebrum
    • Cerebellum
    • Medulla oblongata

Human Brain


  • The cerebrum is the largest part of the human brain.It makes up about 80% of  the mass of the human brain.
  • The cerebrum can be divided into two hemispheres.
    • Right hemisphere
    • Left hemisphere
  • Nerve impulses from the left side of the body will be received by the right hemisphere whereas nerve impulses from the right side of the body will be received by the left hemisphere
  • Functions of the cerebrum are:
    • It controls voluntary and highest intellectual functions such as thinking, learning and problem solving.
    • It regulates emotion and memory through the limbic system.
    • It controls human behavior.
    • Receives and interpets impulses from sensory organs
  • The cerebellum is located below and behind the cerebrum
  • The function of the cerebellum are:
    • Controlling and maintaining posture and balance of the body
    • Controlling and coordinating muscular activities

Medulla oblongata

  • Medulla oblongata is the lower most portion of the brain and is continuos with the spinal cord.It is the smallest component of the brain
  • Medulla oblongata relays nerve signals between the brain and spinal cord.
  • Medulla oblongata controlsn automatic functions
Voluntary and involuntary actions
  • Human respond to a stimulus through voluntary actions and involuntary actions

Effect of injuries to specific parts of the human brain

Hormonal Coordination in the Body

  • are chemicals secreted by endocrine glands.Hormone produced are secreted directly into the bloodstream and carried by blood to tissues or organs without the need of any ducts.They are usually secreted is small amounts
  • The hormones have a specific effect only on the tissue or an organ designed to receive its message .This tissue or organ is called target tissueor target organ.This is because only this specifictissue or organ will respond to them.
  • Important roles of hormones are:
    • causing physical and physiological changes.
    • Controlling the rate of body process
    • Influencing growth
The endocrine system
  • Chemical coordination involves the endocrine glands and their secretion
  • Endocrine system consists of endocrine glands and their secretion
  • Endocrine glands do not have ducts.Thus it is also called ductless glands.

Pituitary gland
  • is located at the base of the brain just beneath the hypothalamus
  • The anterior lobe regulates the activity of several glands.Among these are thyroid,adrenals and reproductive glands.
  • It produces hormones such as:
    • Corticotropin - stimulates the adrenal gland to produce certain hormones.
    • Growth hormone - stimulates the growth of bones, muscles and other body organs.Plays a role in the handling of nutriens and minerals in the human body.
    • Prolactin - promotes the development of glandular tissue in the female breast during pregnancy.Stimulates milk production in women who are breastfeeding.
    • Thyrotropin - stimulates the thyroid gland to produce thyroxine hormones.
  • The posterior lobe of the pituitary gland releases antidiuretic hormones (ADH).This hormone acts on the kidneys to regulate water content and write output.Oxytocin is also released by the posterior lobe.Oxytocin triggers the contraction of the uterus during labour.It also stimulates the ejection of milk from the lactating breast.

Thyroid gland

  • The thyroid gland is located in the front of the lower neck.
  • Hormone thyroxine produced by the thyroid gland has the following functions:
    • Controls metabolic rate
    • Controls skeletal growth
    • Controls mental development
PancreasPancreas produces two important hormones
  • Insulin - insulin decreases blood glucose concentration by stimulating the conversion of glucose into glycogen in the liver.
  • Glucagon - glucagon increases blood glucose concentration by stimulating the conversion of glycogen to glucose in the liver.
Insulin and glucagon work together to maintain a steady level of glucose in the blood.This is important to produce and maintain stores of energy.

Adrenal gland

  • is located on top of each kidney.
  • The adrenal glands have two parts; the internal part is the adrenal cortex and the inner part is name adrenal medulla
  • Adrenal cortex produces hormones called corticosteroids.Corticosteroids influence or regulate salt and water balance in the body, the body's response to stress,metanolism,the immune system and sexual development abd function.
  • Adrenal medulla produces catecholamines such as adrenaline.
  • are located in the female reproductive system
  • Ovaries produce two groups of female sex hormones.
    • Oestrogen
    • Progesterone
  • Oestrogen is involved in the development of secondary sexual characteristics in female such as:
    • The development of breasts
    • The accumulation of body fat aroundthe hips and thighs.
    • Maturation of reproductive organs such as the uterus and vagina.
  • Progesterone prepare the uterus lining for pregnancy
  • is located in the male reproductives system 
  • testis secretes hormones called androgens
  • The most important androgen hormone is testosterone.

Coordination between the Nervous System and the Endocrine System

  • The two types of coordination work together at certain times.The human digestive system is a good example.When food is served,the mouth will start  to salivate and this response is coordinated by the nervous system.Gastrin a type of hormone is secreted when the half-digested food goes into the stomach.Gastrin causes the stomach wall to produce hydrochloric acid and other emzymes to carry out further digestion.

Effects of Drug Abuse on Body Coordination and Health

Definition of drugs

  • Drugs are chemical or biological substances which affect the function of the nerveous system,especially the brain,causing changes in behaviour and personality.They change the way the body works.
Types of drugs
  • The four main types of drugs are:
    • Stimulants 
    • Depressants
    • Hallucinogens
    • Opiates

Drug abuse

  • is the misuse or overuse of any medication or drug
  • Reasons of drug abuse include:
    • use drugs because they are thrill-seekers
    • use drugs out of curiosity or because their friends do it
    • use drugs in order to cope with unpleasant emotions and difficulties in life

Effects of Excessive Consumption of Alcohol on Body Coordination  and Health

  • Ethanol commonly known as alcohol is found in most  alcoholic drinks.It is a strong psychoactive substance with a depressing effect.
  • Ethanol is produced in a process call fermentation.Fermantation is a process that uses yeast or bacteria to change the glucose in the food into ethanol.
                                Yeast  +  glucose  >  ethanol  +  carbon dioxide  +  energy

Effect of excessive consumption of alcohol on body coordination

  • Alcohol is a depressant.This means it slows down the function of the central nervous system.
  • When alcohol is consumed, it is absorbed into the bloodstream rapidly and travels around the body to the brain.

Effect of excessive consumption
  • Alcohol is broken down into acetaldehyde by the enzyme, alcohol dehydrogenase in the liver.The acetaldehyde is then broken down into acetic acid by the enzyme acetaldehyde dehydrogenase.Next acetic acid is converted into fats or carbon dioxide and water.Fatty acids build up as plaques in the capillaries around liver cells.Liver cells begin to die.This leads to the liver disease called cirrhosis.As we know the liver is damaged,certain toxins build up.This leads to sympthoms of jaundice.
  • Foetal alcohol syndrome is another one consequence of excessive consumption of alcohol use.
  • Foetal alcohol syndrome:
    • a foetus is fed through the placenta inside the mother.Since alcohol passes easily through the placenta,the developing foetus gets a dose of alcohol when the mother drinks alcohol.


  • We know that our bodies built from millions Tues In this cell there is a center of activity known as the nucleus. There are chromosomes in the nucleus that contains genes. Gen, this is the nature of our control. For example it controls whether our hair curly or not.
  • Genes are genes that carry material genetic information.
  • Gene located in chromosome. If viewed through a microscope, chromosomes are structures in the nucleus stranded Tues
  • Humans can grow and reproduce because the cell can divide. Two types of cell division is Mitosis and Meiosis. Mitosis occurs in the entire body and cause each day we grow. The number of chromosomes that results remain the same as the original genes [sometimes called the 'master gene']. Meiosis also occurs in the testes or ovaries to produce sperm or ovum. Number of chromosomes in sperm is half the number of cells holding. Human chromosome 23 has a half from Stem cell chromosomes (46 chromosomes).
  • There are many differences between Mitosis and Meiosis


  • Scientists already know that organisms typically have a pair of chromosomes that carry a pair of genes. Genes may be different or the same. There are two types of genes and gene dominant gene resesif.
  • Gene dominant gene is a strong and able to highlight features in the organism. Resesif genes are genes that weak. It can not be met if the features highlight a dominant gene. Gen. 
  • resesif can only highlight the features if he came to the same pair resesif genes.Dominant gene will result in a dominant nature. Based on several examples of genetic research scientist dominant nature of human nature is such as wavy hair and the ability to roll tongue. [the ability to roll his tongue].Resesif properties are properties such as hair is straight and can not roll tongue. How these properties can be handed down from parents to children?.
  • Human cell has 46 chromosomes (23 pairs of genes). Sperm and ovum that results from Meiosis only contain only 23 chromosomes. If the sperm carrying genes that control the nature of curly hair (dominant) ovum mix that brings nature hair straight, then the resulting child will be curly-haired.
  • Chromosome structure in gamet:

  • Chromosomes X and Y chromosome known as the "sex chromosome". This chromosome determines gender of a person.


Sex Choromosomes

  • 22 pairs of choromosomes are known as autosomes.The largest of the autosomes is referred to as chromosome 1,the next largest as chromosomes  2, and so on, down to the smallest autosomes , which are chromosomes 21 and 22.The 23rd pair of the last two chromosomes are known as sex chromosomes.Sex choromosomes are responsible for determining gender.There are two types of sex chromosomes:
    • X chromosomes
    • Y chromosomes

Sex determination

Male chromosomes

  • The human male will have a genetic make up of pairs of autosomes and two types of sex choromosomes X and Y

Female chromosomes

  • The human female will have a genetic make up of 22 pairs of autosomes and only one type of sex chromosomes, XX.

Formation of twins

  • Under normal circumstances, one ovum is released in one menstrual cycle.During fertilision, one ovum will be fertilised by one sperm to produce one zygote.Therefore, a single baby will be born,
  • There are two types of twins:
    • Non- identical twins
    • Identical twins
Non-identical twins
  • More than one ovum is produced in expectional cases.Each ovum will be fertilised by different sperms, developing into zygotes

Formation of non-identical twins

Identical twins

  • Sometimes, one ovum is fertilised and then divides immediately into two  or more zygotes through  division, resulting in twins.

  • The zygotes then develop into two embryos.Both embryos share one placenta with separate amniotic sacs.Babies born in this wy are known as identical twins

                                 Formation of non-idential twins                                               Formation of idential twins

Siamese twin
  • In certain cases identical twins are born joined at identical sides.This happens because the zygote failed to divide completely into two separate embryos.
  • definition of mutation - Human traits can be altered by sudden changes in chromosomes or genes.This is known as mutation
  • Mutation can happen in somatic or reproductive cells.The difference is mutation in somatic cells cannot be inherited by the next generation.
  • Mutation that happens in either the sperm or ovum may be inherited by the next generation although the parents do not possess these traits.
Type of mutationThere are two types of mutation:
  • Chromosome mutation occurs when changes take place in the structure of the chromosome or to the number of choromosomes.
  • Gene mutation occurs when there is a change in the chemocal structure of a gene.
Examples of mutation:
  • Klinefelter's syndrome

Karyotype of an individual with Klinefelter's syndrome
  • turner's syndrome

Karyotype of an individual with turner's syndrome
  • down's syndrome
Karyotype of an individual with down's syndrome

                                                                       Non-disjunction in meiosis I and meiosis II


  • is a condition where there is an absence of the melanin pigment in the skin, hair and iris in human.This condition is caused by a recessive gene taht affects the production of melanin.

Colour blindness

  • Colour blindness is a condition that arises from the mutation of the gene for colour vision.This causes a person to be unable to differentiate between the colour green and red.The mutation produces a recessive gene.


  • is a disease where the blood fails to clot.As a result severe sufferers can bleed to death without treatment .Even if with treatment, internal bleeding  in the joints is the most  problematic complication since  it leads  to paintful arthritis.This disease is an example of a sex-linked disease which is caused by a recessive allele on the X chromosome.


                            Haemophoilia man married to a normal female


                              A normal man married to a carrier female

Causes of mutation

  • Some mutations are induced and others are spontaneous.
  • Mutation is more likely to occur as a result  of exposure to mutagens.Mutagens are factors that cause mutation.Among the known mutgens are nuclear radiations,harmful rays and certain chemicals called carcinogens.
  • Nuclear radiations will penetrate the nucleus of the cell and change the structure of the genes and chromosomes in the nucleus.
  • Harmful rays are also mutagens
  • Chemical - There are many hundreds of known chemical mutagens such as benzene,fungicides,herbicides,insecticides,pesticides and dioxins

Advantages and disadvantages of mutation

Advantages of mutation

  • mutation is one of the sources for the creation of new species.
  • mutation may lead to variation .Variation is the difference in traits between individual of the same species.
  • If no mutation occurs,evolution could not have taken place.In other words mutation is a precursor of the evolution process.
Disadvantages of mutation
  • The disadvantages of mutation to humans can be grouped into:
    • Physical deformities - is a type of physical deformity as a result of mutation.Suffers have extra fingers or toes on both hands or feet.
    • Genetic diseases - Gene mutation many cause genetic diseases such as colour-blindness and albanism.

Effects of Genetic Research on Human Life

Distributions of gebe

  • Amniocentesis is a test perfomed between 16 and 18 weeks of a woman's pregnancy.The drawn fluid is then analysed.This fluid can be tested not only to check  for genetic problems but also to determine the sex of an unborn baby.
  • In gene therapy, a detective gene in unhealthy cells will be replaced with a new and healthy gene by using a type of virus called retrovirus.

Selective breeding
  • Selective breeding is a technique which involves the choosing and breeding of animals or plants with desirable traits to ensure that these traits are inherited by the next generation.
  • Oil palm is the highest yielding oil crop.Selective breeding between the oil palm species Pisifera and Dura to produce a new species called Tenera is a good example.This is shown in Figure 3.32.The oil palm is continually being improved through breeding.

  • Table shows comparison between Pisifera, Dura and Tenera

Advantages and disadvantages of genetic research


  • Vaccines and better medicines are produced in medicine and healthcare through genetic research.
  • The quality of crops and livestock have been improved by genetic research.
  • Crops can be affected by many different diseases.Transgenic plants which are resistant to certain diseases are produced to solve this problem
  • Genetic research may lead to exitinction of species since new varieties replace them.
  • Cloning oe genetic engineering, especially on human beings may give rise to moral,ethical and religious problems.
  • Genetically modified food may be harmful to human health.
  • Ecosystem can also be threatened by genetic technology.

Variation Among Living Things

Definition of variation

  • Variation is the difference in trais of an organism of the same species which can be passed on from one generation to another.
Variation in humans
  • Human differ from each other in terms of 
    • Physical characteristics
    • Physiologically
  • There are two types of variation
    • Continuous variation - differences in traits which are not very distict or discrete.This type of variation tend to be quantitative. controlled by genetic factors and is often significantly affected by environmental influences.
    • Discontinuous variation - is variation which deals with clear-cut differences in traits.Discontinuous variation is completely controlled by genetic factors and is not effected at all by environmental factors.
Factors that cause variation
  • There are two factors that lead to variation:
    • Genetic factors 
      •  variation that is controlled by genetic factors can be inherited.Crossing-over occurs at the start of Prophase I during meiosis.
      • Chromosome separate randomly in gamete formation
      • Random fertilisation
    • Environmental factors
      • environmental factors which cause variation include climate.light, moisture,oxygen,pressure,soil fertility,temperature,type of food and lifestyle.
The importantace of variation
  • The emergence of traits which can adapt well to changes in the environment enables the organism to survive,breed and inherit new characteristics.
  • Variation ensures the survival of a species.Variation may encourage the formation of new species,a process called speciation
  • There will be no diversity in organisms without variation.
Family  tree
  • Pedigree analysis is another term for the construction of a family tree.
  • Pedigree analysis is a schematic chart that shows the flow of a certain trait from parents to the next generation and other related members in a family through inheritance.
  • Table shows a a list of symbols commonly used in a human pedigree analysis. 

Changes in States of Matter
  • All things wheather living or non-living things in the world consist of matter.Matter is any living or non-living thing that has mass and occupies space.Matter is made up of tiny and discrete particles
  • The kinetic Theory of Matter states that matter is mae up of tiny and discrete particles which are always moving in random motion
States of matter
  • Matter exists in three states which are solid,liquid and the gaseous states.
  • All matter whether solid, liquid or in the gaseous state, have the following characteristics:
    • Made up of tiny particles
    • Particles always vibrate and are sometimes moving
    • has space between the particles
  • In the solid state, particules:
    • are arranged in a regular pattern
    • are tightly packed
    • have fixed positions
    • do not move freely
    • only vibrate and rotate around their fixed positions.
  • In the liquid state,particles:
    • are not arranged in a regular pattern
    • are further apart
    • do not have fixed positions
    • move freely around one another
  • In the gaseous state,particles:
    • are not arranged in a regular pattern
    • are widely spaced
    • do not have fixed positions

  • process where solid changes to gas or gas to solid without going htrough the liquid
  • e.g. iodine, dry ice, ammonium chloride and naphthalene

  • can occur because particles move into the space in between the particles of solids, liquids and gases
  • Eg: when 50 cm3 of ethanol and 50 cm of distilled water are mixed,only 98cmof mixture are obtained.This is because the ethanol and water particles occupy each other spaces between the particles.
Brownian motion
  • is random movement example shown by smoke particles or pollen grains when knocked about by air particles

Changes in the state of matter

Impurities like common salt can 

  • increase the boiling point of distilled water (102oc) 
  • lower the freezing point of distilled water (-2oc)
Atom ( a basic unit all matter)
  • all matter consists of tiny units called atoms       

a neutral atom is the number of protons equal to the number of electron (Number of proton = number of electron)
Ion are atoms which have charge:

  • Positive ion = atom which losses of electron
  • Negative ion = atom which receives more electron

Proton number = numner of protons = number of electrons
Nucleon number = total number of protons and neutrons
Isotopes = atoms that posses the same number of proton but different number of neutrons
              = same proton number (chemical properties) but different nucleon number (physical properties)

The periodic table is important in the systematic and methodical study of elements.

Classification of elements in periodic table are arranged orderly and systematically of increasing proton number from left to right based on the number of protons.

Characteristic or Properties of Metals and Non-Metals

Pure substances 

  • Distilled water is pure water because it does not contain any dissolve substance or forein matter.
  • The boiling point of pure water is 100oand melting point is 0o
  • However impurities such as salt can increase the boiling point to 102oc and lower the melting points to -3oc
Purifying substances
  • Distillation
    • is the process of boiling the liquid and condensing the vapour into pure liquid


  • Is forming of pure  crystal from a hot saturated of a salt when it is cooled
  • E.g mining salt from sea water

                                                       Preparing crystals       


5.1 physical and chemical  changes.

  • two types of changes involved in matter:

          *physical changes

          *Chemical changes

Physical Changes

  1. physical change are defined as the changes  that only affect the physical properties of substances.

  2. the characteristics of physical change are:

  • involves only physical changes such as shape or  size of a substance.

  • involves changes in the state of matter;solid,liquid and gas.

  • chemicals composition and chemical properties of substances remain unchanged so that no new substances is formed.

  • less energy is needed.

  • the changes are reversible.

     3.physical changes in our daily life are:

         (a) *Melting of ice:


                *Melting of chocolate.




          (C) *Evaporation of water:


                 *evaporation of alcohol or evaporation of petrol.

           (d)Natural water cycle.




           (f)Dissolving salt and sugar in water.

           (g)Formation  of dew on the grass.

      4.Physical changes being studied in a laboratary are:





  1. Defined as the  changes that affect the chemical composition and chemical properties of the  substances.

  2. the characteristics of chemical change are:

  • new substances known as products.

  • chemical composition and chemical properties of the new substances are different from the original substance which is known as reactant.

  • is usually fixed and irreversible.

  • needs large amount of energy. 

      3.chemical changes in our daily life are:

  • respiration:

  • burning of paper or fossil fuels produces carbon dioxide and ash.

  • digestion of food.

  • washing dishes with detergent or washing hair using shampoo.

  • Change in colour of peeled apple when exposed to air.

  • decomposition of animal carcasses.

  • making bread from wheat flour.

  • photosynthesis.

      4.examples of chemical changes being studied in a laboratary are:

  •       Respiration 

  Oxygen + glucose --------> carbon dioxide + water vapour + energy

  • neutralisation:

    Acid + alkali + -------> salt = water 

  • electrolysis of water.




- chemical reactions involves changes in energy in the form of  heat energy.

- chemical reactions,

  • energy is aborded to break bonds in the reactants.

  • energy is released when new bonds sre formed in the products.

-chemical reaction that absorbs energy is dissolving ammonium chloride in water.when ammonium chloride(Salt) is put into a beaker of               water which is held with our hands,we can feel that the temperature of water falls.this is  because the reaction in the beaker absorbs             energy from the water and our hands.

-Chemical reactions that releases energy is dissolving sodium hydroxide in water.When sodium hydroxide(SOAP) is put into a pail of water          and stirred  using our hands,we can feel  that the soap solution becomes hot.this is because the reaction releases heat into the                    surroundings.



Chemical reactions can be classified into two groups:

  • exothermic reactions.

  • endothermic reactions 

~Exothermic reactions~

  1. exothermic reactions is defined as a reaction which releases energy in the form of heat  into the surrounding (heat loss),and causes the surrounding temparature to increase.

  2. the characteristics of exothermic reactions are:

  • heat is released into the surroundings.

  • Energy is released when bonds are formed because the energy needed to break the bond in the  reactants is less than the energy released when new bonds  are formed in the products.

  • surrounding temperature increases due to the release of energy but the temperature of mixture decreases.

  • Energy content of the reactant(s)

  • Higher energy content of the product(s)

~Endothermic reactions~

     1.~absorb energy or gain heat.

       ~surrounding temperature to decrease.

      2.The characteristics of exothermic reaction are:

  • heat is absorbed.

  • Energy is aborded.

  • surrounding temperature decreases and temperature of the mixture increases.

  • energy  content of the reactant(s) is lower than energy content of the product(s)

     3.endothermic reactions are:

  • boiling water.

  • heating copper sulphate crystals.

  • melting wax.

  • dissolving ammonium chloride in water.

  • photosynthesis.

  • decomposition of mercury oxide by heat and decomposition of copper carbonate by heat.


  • Haber process

  • contact process

haber process

  • ammonia is produced by the haber process on a large scale.

  • catalyst(iron)at atemparature of 450-500°C and a pressure of 200 atmospheres.

  • the process is reversible.

  • heat is released  in the forward reaction (exothermic).

5.3 The reactivity of metals .

  • Activity a chemical reaction.

  • the reactions metals with water.

The  reactivity of metals with water.

  •  Highly reactive metals.

  •  less reactive metals

 The reactivity of metals with oxygen. 

  • metal+oxygen=metal oxide

  • the metal oxide produced a different colour compared to the original metal as shown in table 5.6.


                                                                               TABLE 5.6 


  •  The reaction of metals with water,dilute acids and oxygen will individually produce different chemical substances.

  • table 5.8 shows the comparison of the reactivity of metals with water,dilute acids and oxygen:


table 5.8

 Reactivity series of metals.

  • The reactivity series order of reactivity with oxygen

  • Table 5.9 shows the reactivity series of metals .

                                                          TABLE 5.9


  •  The raectivity series of metals shows the inclination of a metal to react with oxygen.

  • The operatinal definition of this experiment is carbon reduces a metal oxide to its metal if carbon is more reactive than the metal.

  • on the the other hand, carbon does not react with a metal oxide if it is less reactive than the metal.



  •  Table 5.12 shows some common ores.

TABLE 5.12

Two methods of extraction of metals from their ores:

  • Electrolysis of the molten more.

  • reducation of metal ore using carbon

A Suitable method to extract a metal from its ore is based on the position of the metal in the reactivity series of metals as shown in table 5.13.


                                             Table 5.13

The importance of the reactivity series are:

  • Determine the method of extracting the metal.

  • Predict the reactivity of a particular metal.

  • Predict whether a particular metal can remove oxygen from another metal oxide.

The extraction of metals from their ores through reduction using carbon.

  • Metal which are located below carbon in the reactivity series are extracted through the reduction method by carbon.

  • Pure metals which can be extracted using carbon include tin,zinc,copper,iron and lead.

Tin extraction

  • Flotation.

  • Tin extraction Process is carried out in two main stages as follows:

  • impurities,Removed
  • mixed with coke (carbon) and limestone (Calcium carbonate)


  • Decomposition of an electrolyte using electricity.

  • Electrical energy is changed into chemical energy.


  • electrolyte is a compound in molten form or aqueous solution which contains ions.

  • Positive ions (cations) and Negative ions (anions). 


  • Eloctrode Conductor.

  • Carbon rods.

  • anode.

  • Cathode.

Electrical Source

  • Electrical source is the source which generates electrical energy.


  • Ammeter measure the flow of current.

Electrolysis of an electrolyte using carbon electrodes.

  • Electrolysis process is based on the type of electrolyte decomposed and the movement of the ions.

Uses of electrolysis in industry

  • Extraction of  metals

  • Purification of metals

  • Electroplating of metals

Extraction of metals

  • Electrolysis 

  • Extraction of metals.

  • Extraction of aluminium:

  • bauxite

  • melted

  • Mixed with cryolite

  • Cathode

  • Anode

Purification of metals

  • Pure metal electrolysis.

  • Impure metal as the anode

  • Pure metal as the cathode

  • A salt solution as the electrolyte.

Electroplating of metals

  • Electroplating coating of a thin layer of less reactive metal on the surface of another more reactive metal electrolysis.

  • Electroplating a coin with copper.

  • Electroplating an iron nail with copper.

  • Electroplating costume jewellery with gold.

  • Tin plating to produce food cans

  • Silver plating.

  • Electroplating iron nails with zinc.

  • Prevent a metal object from rusting.

  • Make metal look nicer,shiny and attractive.

5.6 The production of electrical energy from chemicals reactions

  • Chemical energy can change into electrical energy.

  • A simple cell is used hoe electrical energy id produced by chemical reaction.

Simple cell.

  • Two different metal plates or carbon plate and a metal plate as electrodes.

  • A dilute acid,an alkali or a salt solution as an electrolyte.

  • The less reactive metal or carbon forms the positive electrode known as the anode

Various types of cells and their uses

  • Production of electrical energy from a simple cell to produce electrical energy.

5.7 Chemical reactions that occur in the presence of light.

Chemical reaction which require light.

  • Some reactions need light energy to start a chemical reaction.

  • Photosynthesis.

  • Photographic film.

  • Silver chloride.


  • Green plants synthesise food using chlorophyll pigment,light energy,water and carbon dioxide.

  • Hydrogen and oxygen as photolysis of water.

  • Dark reaction;

  • Food or glucose.

Effect of light on photosensitive chemicals

  • Is sensitive to Light is known as a photosensitive chemical.

  • Photosensitive chemical are:

  • Silver chloride.
  • silver bromide.
  • Silver iodide.
  • chlorine water.
  • hypochlorite solution
  • silver nitrate

5.8 Innovative efforts in the design of equipments using chemical reactions as sources of energy

  • Electrical energy

  • using ellectrical energy efficiently.


6.1 Radioctive substances

  • Unstable nucleus.

  • Radioactive substances are:

  • Uranium

  • Polonium

  • Radium

  • Radioactive isotopes or radioisotopes.

  • Examples of radioisotopes:

  • Uranium-235,uranium-238

  • Radium-226

  • Polonium-212

  • Carbon-14

  • Cobalt-60

  • Phosporus-32

  • Sodium-24

  • Hydrogen-2,hydrogen-3

Radioactive decay

  • Nuclei energy is produced.

  • Three types of radiations:

  • alpha(α)

  • beta(β)

  • Gamma(γ)

The uses of  radioactive substances

  • Agriculture

  • Medicine

  • Archaeology;

  • Carbon Dating.

  • Industry

  • Food preservation

6.2 Production of Nuclear Energy and Its Uses

  • Nuclear energy is released

  • Radio active decay and nuclear reaction

  • Two types of nuclear reactions:

  • Nuclear fission

  • nuclear fusion

Nuclear fission

  • An unstable nucleus is bombarded by high-speed neutrons,Form more stable nuclei.

  • Nuclear energy produced by nuclear fission is used to generate electricity.

  • Nucleus of uranium -235 is bombarded with high-speed neutrons.

  • Nucleus will absorb the neutron and split in two nuclei.

  • Two nuclei are radioactive barium-141 nucleus and krypton-92 nucleus.

  • Three new high-speed neutrons are produced.

  • a large amount of nuclear energy is released.

Nuclear fusion

  • Two light nuclei combine to form a heavier nucleus.

  • Nuclear energy. 

Nuclear fusion of hydrogen isotopes:

  • Very high temperature and pressure,hydrogen-2 and hydrogen-3 isotopes fuse and form a helium nucleus.

  • Total mass after nuclear fusion is slightly lower than the mass before nuclear fusion.

  • Loss in mass is converted into large amount of nuclear energy and a neutron is released.

The uses of nuclear energy.

  • Used to propel vessels such as submarine and aircrafts which allow them to operate for one or two years without having to refuel.

  • Besides solar energy,Nuclear energy is the major source of energy that enables the satellites to operate for years.

  • Nuclear energy is mainly used to generate electricity.

Process of generating electricity from nuclear energy.

  • Uranium rods,Radioactive substances.

  • graphite rods,control the rate of chain reactions.

  • Heat energy ,boil water.

  • Steam rotates the turbine,produce electricity

  • Condenser,Condense steam.

The effect of nuclear energy production

                                                           table 6.2

6.3 The Need Proper Handling of Radioactive Substances

  • In 1986,a fire in a nuclear power plant in cherynobyl,Russia.This incident caused:

    • The death of thousands of people.

    • About 24 000 people will die of cancer in the next 70 years.

    • Farm and diary products in europe were polluted with radioactive substances .

    • The city was completely destroyed. 

  • Proper safety measures should be taken when handling radioactive substances in order to prevent:

    • Nuclear disaster such as in chernobyl,Russia.

    • Radioactive contamination.

    • Health problem such as cancer.

    • genetic mutations .

  • Effect of radioactive radiations on living things can be categorised into short and long term as shown in table 6.3:

                                                              Table 6.3

Correct ways of handling radioactive substances and radioactive wastes.

Symbol represent radioactive substances:


          Figure 6.6

  • Low-level wastes

  • Intermediate-level wastes

  • High-level waste

    7.1 Formation of images by plane mirrors and lenses.

    Formation of images by plane mirrors.

    • Virtual.

    • upright.

    • Laterally inverted

    • Same size.

    • Distance image behind the screen same as the distances of the object.

    Characteritics of images formed by convex and concave lenses.

    • A lens transparent material glass or plastic.

    • Convex lens.

    • concave lens.

                                                                    Table 7.2
    • Table 7.4 shows the comparison of images formed by a convex and a concave lens .

                                                               Table 7.4

    Ray diagram

    • A ray diagram shows the path of light rays passing through a lens.

    • A ray diagram is drawn using two rays from a point on the object as shown in table 7.5:

    • The ray diagram and the characteristic of images formed by convex lens is different according to the object distances as shown in table 7.6.


    Focal length.

    • Focal length is defined  as the distance between the focal point and the optical centre.

    • The symbol for local length is 'f '.

    7.2 Formation of images by optical instruments

    Identifying parts of optical instruments involved in image formation



                                         Figure 7.5 Periscope

    • Virtual

    • upright

    • The same size as the object.

    • Image distance.

    • same object distance.


    • Two convex lenses.

    • Virtual

    • Inverted.

    • Bigger.

      Figure 7.6(a) Telescope

    Magnifying glass

    • Virtual

    • Upright

    • Larger

                 Figure 7.7(a)Magnifying glass.

    Pinhole camera


                                  Figure 7.8 Pinhole Camera

    • Real and inverted.

    • Size of the image dependent on the object distance in front of the pinhole camera.

    • Number of image dependent on the number of pinholes.


    • Lens.

    • Diaphragm.

    • Aperture.

    • Focus adjustor.

    • shutter.

    • Film.

    • Nearby object,lens is adjusted away from the film.Distance between the lens and the film is increased.

    • Distant object,Lens is adjusted towards the film.The distance between the lens and film is decreased.

    • diaphragm control the amount of light entering the lens.Aperture focal length of the camera lens.

    • Shutter.

    Table 7.9 shows effect of the light condition due to the size of the 

    diaphragm opening and the speed of the shutter opening.

                                                                    Table 7.9

    • Film capture the image of the object.

    • Real,inverted and smaller.

    The human eye as an optical instrument.

                           Figure 7.10 structure of the human eye.


    • Image are formed here.It contains thousands of light sensitive cells which send nerve impulses when they receive light.

    Optic nerves

    • Carries nerve impulse to the brain to be processed.


    • The thickness of the lens can be altered to control the focus of the eye.


    • Light enters the eye through this opening,it appears black.


    • Helps to focus light onto the retina by refracting light rays that pass through it.


    • Control the size of the pupil.

                                        Table 7.10 Function of main parts of the human eye.

    • Ability of the eye lens to change its focal length accommodation.

    Dim lights

    • Radial muscles contract,circular muscles relax.

    • Size of the pupil bigger.

    Bright light

    • Radial muscles relax.

    • circular muscles contract.

    • Size of the pupil smaller.

    Comparing the human eye with a camera.

    The structure and function of various parts of human eye using the camera as an anology.


    Table 7.12 shows the analogy between the structure and function of the eye and a camera. 

    7.3 Dispersion of light.

    Dispersion of light.

     Dispersion of light by a prism

    • Light dispersion light is split colour consituents Spectrum passes through a glass prism.

    • Red,Orange,yellow,green,blue,indigo and violet.

    Formation of the rainbow

    • Dispersion of light.

    • Two refraction.

    • One reflaction.

    • Primary rainbow.

    • Two refraction.

    • Two reflaction.

    • Secondary rainbow.

    7.4 Scattering of light.

    • Wavelength of the light.

    • Shorter more scattered.

    Scattering of light in natural phenomena.

    • At noon:

      • Short wavelength scattered more.

      • sky blue.

      • Eyes more sensitive to blue light.

    • At dawn or dusk:

      • Short wavelength scattered more..

      • Long wavelength Scattered less.

      • Sun reddish if polluted with dust.

    7.5 Addition and substraction of coloured light.

    • Primary colours;

      • Red

      • Blue

      • Green

    • Secondary colours;

      • Yellow

      • Magenta

      • cyan

    Addition of coloured light.

    • Process two primary coloured lights overlap.

                                                              Table 7.14

    Subtraction of coloured lights by coloured filters.

    • Enables a particular coloured light to pass through it.

    Primary filter.

    • Red,green,and blue filters.

    • Allows lights of the same colours to pass.

    Secondary filter.

    • Yellow,magenta and cyan filters.

    • allows lights of the same colours and primary colours that from them.

                            Table 7.29

    7.6 Using the principle of substraction of coloured lights to explain the appearance of coloured objects.

    • Primary coloured reflect its own colour.

    • Secondary coloured reflect its own colour and the colours that form it.

    Table 7.16 shows the summary of the principle of subtraction of coloured lights in the appearance of an object.

                                                            Table 7.16

    Function of rod and cone cells in the eye.

    • Rod cells:

      • Sensitive to low intensity light.

      • Red

      • Green

      • Blue

    • Cone cells:

      • Sensitive to coloured light.

    7.7 The Effects of Mixing Pigments.


    • Substract and reflects certain colours in light.

    • Living things such as plants and animals.

    Uses of pigments.

    • Textile industry

    • Food industry 

    • Cosmetics industry

    • Printing industry

    • Painting industry

    • Natural world

    Effects of mixing pigments.

    • Primary colours:

      • Red

      • blue 

      • Yellow

      • Except white.

    Mixing of coloured pigment produces colours as shown in table 7.17.

                                                               Table 7.17

    Coloured lights reflected by different coloured pigments in white lights as shown in table 7.18.

                                                                                                                       Table 7.18

    Comparison between the coloured pigments and coloured light from different aspects as shown in table 7.19.

                                                             Table 7.19

    7.8 The importance of colour in daily life.

    • Colour printing.

    • Electrical wiring.

    • Traffic lights.

    • Symbols and signals.

    • Survival of living things.

    • Colour television.

    Colour printing

    • Yellow,magenta,cyan,and black.

    • Colour separation.

    • Printing plates.

    • Black ink to sharper clearer.

    Electrical wiring

    • Brown for live wires.

    • Blue for neutral wires.

    • Yellow and green stripes for earth wires.

                        Figure 7.35

    Traffic lights

    • Red.

    • Yellow.

    • Green.

                  Figure 7.36

    Symbols and signals.

    • Two white lines in the middle of  the road indicate that no overtaking is permitted.

    • Yellow line painted side of the road ,Cars cannot be parked along the side of the road.

    • Yellow box painted with yellow stripes,Cannot stop inside the box.

    • Small red flag is raised when an event is being is being prepared,Small green flag is raised when the event is ready to begin.

    • Ambulance red light indicates an emergency.

    7.9 Appreciating the benefits of various types of optical instruments of to mankind.

    Table 7.20 shows optical instuments and their uses.


                                                          Table 7.20



    8.1 Properties of alloys and Their uses in industry.


    • Homogenuos mixture pure metal another pure metal or Non metal.

    • Alloying mixing other elements to the pure metal.

    • Alloying process is carried out as follow:

      • A pure metal is melted
      • some metal and non-metal are then added to the molten metal
      • The mixture is the cooled

                                                                Table 8.1

    Alloying Changes the properties of metals.

    • Weakness and structure of a pure metal are improved by alloying.

    • Pure metals become more resistant to corrosion,shinier,more attractive appearance and harder.

    Prevents corrosion of metals.

    • Alloying.

    Improves the appearance of metals.

    • Copper has dull brown surface after being oxidised.

    • Alloying prevents rust,most alloys,nice shiny surface.

    • Examples:

      • A little nickel is added to copper to produce copper  nickel alloy.

    Increases the hardness and strength of metals.

    • Metal such as magnesium,aluminium are soft and light.

    • Problem can overcome by alloying.Alloys are harder and stronger.

    • For example:

      • Magnesium is mixed with aluminium to produce magnalium.Magnalium is an alloys are hard but it still retains the lightness of both  these pure metals.

    Arrangement of particles in alloys and the uses of alloys

    1. Atoms of pure metals are arranged very closely and orderly as shown in figure 8.1.


                         Figure 8.1

         2.The layers of atoms slide easily over one another when a force is a result,it becomes ductile as shown in figure  8.2.

                        Figure 8.2 Ductile property of metal.

         3.Ability of the layers metal atoms to slide easily also makes it malleable and easily shaped when a forced is applied as shown in figure 8.3.

                     Figure 8.3

    In an alloy,substances added which are smaller or bigger fill the shapes between the pure metal atoms and the new arrangement is formed as shown in figure 8.4.

                                 Figure 8.4 Alloy with smaller atoms.

    • Prevents the layers of pure metal atoms from sliding over one another.

    Table 8.2 shows the comparison between a pure metal and alloy.

                                                             Table 8.2

    The importance of alloys in industry.

    • Carbon steel.

    • Stainless steel resistant to corrosion.                                                    

    Supercondutor alloys.

    • Differences ordinary conductor(Normal conductor) and superconductor.

                        Figure 8.5

    Table 8.3 shows uses of superconductor alloys in industry and daily life.

                                                              Table 8.3

    8.2 Production and uses of ammonia in industry.


    • Pungent smell,colourless and very soluble in water.

    • ammonium hydroxide.

    Uses of ammonia and its compound in daily life.

    • Table 8.4 shows uses of ammonia and its compounds in daily life.

                                                 Table 8.4

    Production of ammonia in industry.

    • Haber process produce ammonia.

    • Nitrogen and hydrogen.

    • Hydrogen is produced by reacting methane with steam or from the cracking oil. 

    • Iron powder is added  as a catalyst.Booster like aluminium oxide.

    • The following shows  the reaction  in producing ammonia.    


    • Reversible.


           Figure 8.6 The haber Process

    • Factor influencing the production of ammonia:

      • Pressure 200-500 atmospheres. 

      • Temperature Exothermic 450-500ºC

      • Catalyst increase the rate of a chemical reaction boosters activate the catalyst.

    Uses of ammonia in industry.

    • Ammonia is also used in large quantities to produce Nitric acid.

    Production of ammonium fertilisers.

    • Natural fertiliser.

    • Synthetic fertiliser.

    Production of ammonium salt fertilisers.

    • Ammonium nitrate

    • Ammonium sulphate

    • Ammonium phosphate

    • The preparation of ammonium salt fertiliser in the science laboratory is as follows:

    Production of urea.

    • Urea is produce through the following processes:

      • Heated  200ºC and pressure of 200 atmospheres.

      • Separated

      • dried

    • The reaction between chemicals which produce urea is shown below.

    8.3 Effects of industrial waste disposal on the environment.

    • Poisonous and harmful industrial activities causes the quality of the environment to be on the decline.

    • the two main pollution-causing industrial activities  are:

      • The burning of fossil fuels.

      • the direct disposal of industrial wastes from facrtories.

    Sources of pollution from manufacturing activities and the effects of imporer industrial waste disposal .

    Burning of fossil fuels.

    • Fossil fuels such as diesel,oil and natural gas are burned in factories and electric power stations to generate heat energy and electrical power.

    • Gases such as carbon dioxide,carbon monoxide,sulphur dioxide,and nitrogen dioxide are released.because fossil fuels have high contents of carbon and sulphur.

    Greenhouse effect.

    • Earth receives most of its energy from the sun.Energy is used to heat up the Earth's surface.Heat produced is in the form of infrared radiation.It reflects heat back into the atmosphere.70% of the sun's energy is radiated back into space.Earth is kept warm enough to support life.

    • Increase Earth's temperature by trapped heat in the atmosphere as shown in figure 8.8.

                                                                      Figure 8.8 the green house effect

    The greenhouse effect also causes other problems such as:

    • The weather becomes warmer.

    • The melting of ice.

    • desert areas bigger.

    • Global warming.

    Figure 8.9 shows the contribution of different types of greenhouse gases towards global warming.

                                          Greenhouse gases that contribute

                                                  towards global warming

                         figure 8.9

    Acid rain

                          Figure 8.10 Formation of acid rain 


    sulphur dioxide contributes to acid rain

    Oxides of nitrogen contribute to acid rain.

                              Figure 8.11

    The effects of acid rain:

    • Disturbs the equilibrium of nature

    • Acid rain affects lakes,streams,rivers,bays,ponds and other sources by increasing their acidity.This leads to the death aquatic organisms and plants.

    • Destroys plants and trees as the soil becomes too acidic.

    Chemical industry.

    • Toxic chemicals,oils and untreated waste.

    • Pollutants also affect quantity of dissolved oxygen,affecting aquatic animals and plants.

    Nuclear power stations and research institutions.

    • Radioactive produced nuclear research centres,nuclear reactors and manufactring products contain radioactive substances.

    • Radioactive radiations released by these sources into the surrounding. 

    Agriculture industry.

    • Oil palm industry

      • Oil palm industry are stalks of fruit branches,fibre wastes and oil spill.

      • Oil palm wastes are disposed off by burning them or leaving them to rot.

    • Rubber industry

      • Rubber wastes are made up of phospate salt,ammonia and rubber protein.

      • These wastes encourage the growth of bacteria.

    Table 8.5 shows the types of pollutants,their sources and effects on living organisms.


                                                         Table 8.5

    Method of controlling industrial waste disposal.

    Several ways to control the disposal of industrial wastes such as:

    • Law enforcement

      • Environmental Quality (scheduled wastes)Regulation,1989

      • Environmental quality (Clean air)Regulation,1979

    • Recycling wastes

      • Variety of industrial wastes recycled for use as products.

      • Particulars industry can also be used by other industries if that industries if that industrial waste is suitable for them.

    • Education

      • Public need to be educated about the importance of environmental cleanliness and the harmful effects of environmental pollution.

      • The mass media and schools plays important roles in spreading environmental awareness to the public.

    • Technology

      • Biogas technology

      • direct burning

      • Disposal drums

      • Using electrostatic precipitator

      • Using a scrubber

    Biogas technology

    • Process agricultural wastes naturally through digestion by microorganisms.

    • Anaerobic microorganisms.

    • Inside a digester drum called the Digester unit.

    • Temperature 30 ºC - 40 ºC

    • Biogas.

                                          Figure 8.12 biogas digester

    • The separated  methane is sent to houses for cooking purposes or to factories for Heating purpose.

    • Electrical energy.

    Direct burning

    • Agricultural wastes are directly burned in a heating furnace.

    • Figure 8.13 shows the system which is used to burn agricultural wastes.

    Figure 8.13 Component of the direct burning system.

    Disposal drum

    • Radioactive waste is radioactive material which may be left after a commercial or laboratory process has been carried out.

    • Radioactive wastes disposal drums which are made of strontium.

    • Disposal drums placed 200 metres below the soil surface.

    Using electrostatic precipitor.

    • Electrostatic precipitator two collection plates:

      • Positive plate

      • Negative plate

    Using a scrubber.

    • Scrubber is used to filter the poisonous gases by sparing a liquid onto the poisonous gases.

    • The toxic-free gas is then released.

    • figure 8.14 shows an air scrubber.

                          Figure 8.14 Air scrubber.

    8.4 Preservation and Conservation of the Environment.

    • Preservation Environment refers to steps taken to maitain the environment as close to its Natural state as possible.

    • Conservation refers continuos managment of the environment to minimise damage to the environment.

    Consequences of uncontrolled and haphazard disposal of industrial wastes.

    • Earth is in real danger.This can be proven through headlines in newspapers about the uncontrolled and haphazard disposal of industrial wastes.

    • Indusrtrial wastes can pollute water sources.Water sources become unsuitable for human consumption.Water pollution also threatens aquatic lives.

    The importance of practising responsiblity in disposing wastes.

    • Humans must practice responsibility.

    • All wastes produced by industries must be stored,transported and disposed off properly.

    • A pollution-prevention hierarcy which emphasies on reducing the amount of toxic waste produced as shown in figure 8.15 must be implemented .stratergies involved include:

      • Reduce the amount of pollution at the source.

      • Recycle wastes wherever possible.

      • Treat wastes to minimise their hazards.

      • Disposal of wastes on land is carried out only as a last resort. 

          Figure 8.15 the pollution-prevention hieracy

    • Several ways to preserve and conserve the environment which include:

      • Control by authorities.

      • Education.

      • Use of technology.

    Control by authorities.

    • The following laws are used to control the disposal of industrial wastes:

      • The Environmental Quality act 1974(Amendment 1985).

      • The Factory and machinery Act 1976(Revised 1983).

      • The pest Poison Act 1874

    • The government organised and participated in international conferences to discuss environmental world issues.There are:

      • The langkawi declaration (october 1991).

    • The Earth summit conferences (1992).

    • The agreements made in this conferences include:

      • Reducing the emission of carbon dioxide gas that causes global warming.

      • The protection of animals and plants to ensure they do not become extinct.

    • The Earth summit resulted in the following documents:

      • Agenda 21 

      • convention on biological diversity

      • Forest principles 

      • Rio declaration on Environment and development.

    Educating the public.

    • Every citizen has a responsibility in looking after the cleanliness and purity of the environment.

    • The preservation and conservation Environment can be spread through campaigns,mass media and the school syllabus.

    Use of technology.

    • Pollution reduced by using modern technology.

    • Factories reduce pollutants in the air by installing filters.



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