QUESTION ANSWER 1.State the kinetic theory of matter
State one example to support the kinetic theory of matter
-Matter consist of molecules. These are the smallest particles, which are capable of free existence and retain all the chemical properties of the parent substance.
-The molecules are always in a state of random continuous motion.
-The molecules exert forces on one another. These forces depend upon intermolecular distance. Gas.
2.What are atom,molecule,and ion Atom-smallest particle that can participate in chemical reaction
Molecule-Group of 2 or more atoms which are chemically bonded together
Ion-Charged particle
3.What is melting point? Melting Point-The temperature that remains constant at which a solid changes into a liquid at aparicular pressure
4.Define proton number and nucleon number Proton Number-The number of proton presence in an atom
Nucleon Number-The total number of proton and neutron in an atom
5.State the meaning of isotopes -Atoms of the same element with the same number of proton but different number of neutrons
6.State the uses of isotopes such as carbon-14 and cobalt-60
Cobalt-60:Radiotheraphy of treating cancer Carbon-14:Carbon dating(estimate age of fossils and artefacts)
7.Explain why the temperature remains unchanged during the melting process
-This is because the heat energy absorbed by the particles is used to overcome the forces of attraction between the particles
8.Explain why the temperature remains unchanged during the freezing point
-This is because the heat loss to the surrounding is balanced to the heat energy liberatedas the particle attracts one another to form solid
9.A solid compound is heated until it converts into gas.Explain the changes in energy
content,forces of attraction between the particles and arrangement of particles
-When a solid is heated,the particles in the solid absorb heat energy and vibrate stronger at its fixed position due to the increase in kinetic energy of the particles .When the particles managed to overcome the strong force of attraction between them they will finally changed into liquid.In liquid form,the particles have a higher amount of kinetic energy than it is in solid and they can move in a
more random manner.When it reaches the boiling point,the particles can move freely and in a
random manner as it has changed its state into gas which has the highest kinetic energy and the weakest force of attraction between particles
SOLID LIQUID GAS
-Low Kinetic Energy -Kinetic Energy is lower than it is in solid and higher than gas -Low kinetic Energy -High Force of Attraction Between Particles -Force of attraction between paricles are as strong as it is in solid -Low Force of attraction between particles -Particles are Arranged in orderly manner -Rotate and vibrate at fixed position only -Particles are closely packed together but can move in a random manner -Particles can move freely and randomly
10.State the main subatomic particles of an atom.
Compare and contrast the relative atomic mass and the relative charge of the subatomic particles of the atom
Subatomic Particles Relative Atomic Mass Relative Charge Proton 1 +1 Neutron 1 0 Electron 0.0005 -1
11. is the symbol of aluminium
a)Determine the number of neutron of aluminium
b)Draw the electron arrangement of aluminium
a)Neutron number=14 b)
12.Solid Z has a melting point of 65C.Describe a laboratory experiment to determine the melting point of Z.Your answer should show how the melting point of Z is determined
1.A boiling tube is filled with solid Z to a depth of 3cm and thermometer is put into it
2.The boiling tube is suspended in a beaker half filled with water using a retort stand and
clamp.The level of solid Z in the boiling tube must be below the level of water in the beaker.
3.The water is heated and the solid Z is stirred slowly with the thermometer.When the temperature of the solid Z reaches 450C,the stopwatch is started.
4.The temperature and the state of substance Z is recorded at half minute intervals until the
temperature of substance Z reaches 800C. 13.Compound W has a freezing point of
82C.Describe a laboratory experiment to determine the freezing point of W
1.Step 1 to 2 of the above experiment is repeated using compound W instead.
2.The water is heated and the compound W is stirred slowly with the thermometer.When
compound W reaches 950C,the heating is stopped 3.The boiling tube is removed from the water bath and the outer surface is dried up.Then it is
immediately put into a conical flask with half of the top of the boiling tube clamped using a retort stand.The compound W is stirred continuosly. 4.The temperature and the state of compound W is recorded at half-minute intervals until the temperature drops to about 750C.
QUESTION ANSWER 1.State the meaning of relative atomic mass
based in carbon-12 scale
-Number of times the mass of an atom is greater than a/12 times of the mass of a carbon-12 atom. The relative mass of carbon-12 atom is 12.000. 2. Define a mole -An amount of substance that contains as many
particles as the number of atom in exaclt 12g of carbon-12
3.State the meaning of molar mass -Mass of 1mol of substance of units,molecules or atoms.
4.State the meaning of molar volume of gas -The volume occupied by one mole of gas. 5.State the meaning of empirical formula -The formula that shows the simplest whole
number ratio of atoms of each element in the compound.
6.State the meaning of molecular formula -The formula that shows the actual number of atoms of each element that is present in a molecule of the compound
-Molecular formula=(empirical formula)n 7.Explain why we couldn’t determine the
empirical formula of copper()oxide by heating copper powder in a crucible
-This is because copper is not a reactive metal so it will take a long time for It to react with the oxygen in air.Thus,to determine the empirical formula of copper()oxide,another method is used.The method uses continuous flowing hydrogen gas to obtain copper metal from the reduction of copper()oxide.
8.Compare and contrast empirical formula with
molecular formula using ethane as an example Ethane
Empirical Formula Molecular Formula
CH3 C2H6
9.Vinegar is a dilute ethanoic acid with a molecular formula CH3COOH.
a)Find the empirical formula of ethanoic acid b)Find the percentage composition by mass of carbon in ethanoic acid
a)Empirical Formula:CH2O
b)Percentage of carbon in ethanoic acid=2(12) 100%=40% 2(12)+4(1)+2(16)
10.3.6 of carbon reacted with 0.8g of hydrogen to form a compound
a)Determine the empirical formula of the compound formed
b)Given thet the relative molecular mass of the compound is 88g,find its molecular
formula.[Relative atomic mass:Cu,12;H,1]
a) Carbon Hydrogen Mass(g) 3.6 0.8 No.of Moles(mol) 3.6÷12=0.3 0.8÷1=0.8 Ratio of moles 3 8
Thus,the empirical formula of the compound is C3H8
b)(C3H8)n=88
(3(12)+8(1))n=88 n=
=2
Thus,the molecular formula of the compound is C6H16
11.Hydrogen gas is reacted with 20g of hot
copper()oxide powders to produce solid copper and water
a)Write the chemical equation for the reaction b)Calculate the maximum mass of solid copper formed[Relative atomic mass:Cu,64;O,16;H,1]
a)Cuo+H2→Cu+H2O
b)No.of moles of CuO=20g+(64+16)gmol-1 =0.25mol
Ratio of moles CuO:Cu=1:1 So Cu has 0.25mol.
Mass of Cu=0.25mol x 64gmol-1 =16g
12.Describe a laboratory experiment to
determine the empirical formula of magnesium oxide and copper()oxide
Your answer should include all the precautions and calculations involved’[Relative atomic mass:Mg,24;O,16;Cu,64;H,1]
Title Empirical formula of copper(II) oxide
Aim To determine the empirical formula of copper(II) oxide Problem
Statement
How does the formula of copper(II) oxide determine? Hypothesis The empirical formula of
copper(II) oxide can be
determined by finding out the mass of copper and oxygen in a sample of copper(II) oxide
Apparatus U tube Stoppers Glass tube
Combustion tube with a small hole at the end
Retort stand and clamp Spatula
Bunsen burner Balance
Preparation for hydrogen gas Thistle funnel
Flat-bottomed flask Material Hydrogen gas, H2
Copper(II) oxide
Anhydrous calcium chloride, CaCl2
Wooden splinter
Preparation for the hydrogen gas
Dilute hydrochloric acid Zinc pieces
Variables Manipulated variable: Mass of copper oxide
Responding variable: Mass of copper formed
Controlled / Fixed variable: An excess of hydrogen gas
1.State the basic principle of arranging the elements in the Periodic Table from its proton number
Increasing the proton number
2.State the physical properties of Group 1 -Atomic size increases-When going down the group,the number of shells occupied with electrons increases
-Density increases-The increase in atomic mass is bigger than the increase in atomic radius.
-Melting and boiling point increase-The metallic bond between the atoms becomes weaker down the group as the atomic radius increase.Thus less heat energy is required to overcome the weaker forces of attraction between the atoms during melting/boiling
-Electropositivity of the metals increases-As atomic radius becomes larger down the group the force of attraction between the nucleus and the single valence electron becomes weaker.Hence,the elements lose the single valence electron more easily down the group.
-Reactivity Increase-Reactivity increases because the atomic size increase,the valence electron in the outermost shell becomes further away from the nucleus.Hence,the atoms can easily donate the single valence electron to achieve the stable electron arrangement of the atom of noble gas. 3.State the physical properties of Group 17 -Reactivity Decrease-This is because the atomic
size of halogen increases.Thus the outermost occupied shell of each halogen atombecomes further from nucleus.Thus,the strength to attract one electron into th valence shell by the nucleus become weaker.
4.State the changes in the atomic size and the electronegativity of elements across Period 3
Atomic size decreases from left to right
-The proton number increases from left to right -The nuclei charge,positive charge in the nucleus increases
-Nuclei attraction force between the nucleus and the valence electron increase
-Valence electron becomes closer to the nucleu -Thus,atomic size becomes smaller
When across period 3 from sodium to argon,the electronegativity increases
5.State three special properties of transition elements
-The elements from group 3 to group 12 in the periodic table
-Has high melting and boiling point -has high tensile strength
6.State the position of element in Periodic Table.Explain your answer
-Element X has an electron arrangement of 2.8.8.2.Hence,it is positioned at period 4 group 2.(Period=no of shells;Group=valence number) 7.When across Period 3 from sodium to
argon,the atomic size decreases.Explain why.
-This is because the number of proton increases from left to right.This causes the positive charge in the nucleus to increase.The nuclei attraction force between the nucleus and the valence electron increase.The valence shell containing valence electron becomes closer to the nucleus.Hence,the atomic size decreases from sodium to argon. 8.When across Period 3 from sodium to
argon,the electronegativity increases.Explain why.
-This is because the number of proton increases from left to right.This causes the positive charge in the nucleus to increase.The increase of proton causes valence shell containing valence electron to be closer to the nucleus.The more the proton number,the stronger the force to attract valence electron and electrons into the valence
shell.Hence,the electronegativity increases across period 3
9.The reactivity of group 1 increases when going down the group.Explain why.
-Reactivity increases because the atomic size increase,the valence electron in the outermost shell becomes further away from the
nucleus.Hence,attraction between nucleus and valence electron becomes weaker.Thus,the atoms can easily donate the single valence electron to achieve the stable electron arrangement of the atom of noble gas
10.The reactivity of group 17 decreases when going down the group.Explain why.
-This is because the atomic size of halogen increases.Thus,the outermost occupied shell of each halogen atom becomes further from
nucleus.Thus,the strength to attract one electron into the valence shell by the nucleus becomes weaker.
11.Why helium gas in not reactive? -This is because it is a noble gas which has octect electron arrangement.Thus,it does not need to receive or losses any electron making it not reactive.
12.X in an element from Group 1.X burnt in oxygen and the products is dissolved in water.What is the property of the solution formed?Explain why.
-The solution form is an alkaline solution.It reacts with acid to form salt and water.The solution formed has this characteristic because group 1 elements are alkali metals whereby its oxide can dissolve in water to form alkali(XOH).
13.Chlorine gas is dissolved in water.What can you observe is a piece of blue litmus paper is immersed into the solution formed?Explain why.
-Chlorine water changes the blue litmus paper into red then white.This happens because chlorine gas is an acidic gas and when it dissolves in water,its acidic properties are displayed and it becomes hydrochloric acid.The litmus paper hten changes into white as the solution has bleaching
properties(HOCl) Cl2+H2O HCl+HOCl
14.W is an element from Group 1.Predict the chemical reaction of W with:
a)water b)oxygen
State the observation and write the chemical equation involve.
Reaction With Observation Equation
Water It reacts quickly with water.The solution formed changes the red litmus paper into blue 2W + 2H2O 2WOH + H2 Oxygen It bums brightly with flame.White solid is produced and it dissolves in water.The solution formed changes red litmus paper blue 4W+O2 2W2O W2O+H2O 2WOH
15.Describe a laboratory experiment to compare the reactivity of elements in Group
1:lithium,sodium and potassium.
16.Describe a laboratory experiment to compare the reactivity of chlorine,bromine and iodine in the reaction with iron wool.State the observation and write the chemical equations involve in reactions.
1.What is anion? -A negatively charged ion
2.What is cation? -A positively charged ion
3.State two physical properties of ionic compounds
4.State two physical properties of covalent compounds
5.Explain why sodium chloride can conduct electricity in aqueous state but cannot conduct electricity in solid state.
-This is because in aqueous state the ions that made up sodium chloride are able to move freely in the solution.This means that there are charges moving in the solution.Hence,it can conduct
electricity.However,in solid state,the ions are at fixed position in lattice.They are unable to move around freely.Thus,it cannot conduct electricity.
6.Magnesium chloride and hydrogen chloride are two compounds of chlorine.At room condition,magnesium chloride exists as a solid but hydrogen chloride exists as gas.Explain why. Magnesium chloride Aspects of view Hydrogen chloride Solid State at room temperatue Gas
Ionic compound Type of compound Covalent comppund High Boiling point Low Ionic compound is held together by a strong bond called ionic bond.This means that more heat energy is needed to break the bonds and change the state of the compound.Hence,at a moderate room temperature it is in solid state Inference Covalent compound is held together by weak intermolecular forces(Van-der-Waals force).This means that a small amount of heat energy is sufficient to change its state.Hence at a moderate room temperature it is in gas state
7.Describe the formation of ionic bond in sodium chloride,NaCl.
-A sodium atom has 11 electrons and it has an electron arrangement of 2.8.1.This electron arrangement is not stable.It needs to donate an electron to achieve an octet electron
arrangement.When a sodium atom donates an electron,it will become sodium ion with the electron arrangement of 2.8.
-Chlorine atom has 17 electros and it has an electron arrangement of 2.8.7.This configuration is unstable.It needs to receive one electron to become stable and achieve an octet electron arrangement.When a chlorine atom receive electron,it will become chloride ion with the electron arrangement 2.8.8. -When a sodium atoms reacts with a chlorine atom,an electron of the sodium atom is given to the chlorine atom.The positively charged ion Na+ will attract to the negatively charged ion,Cl- to form an ionic compound,sodium chloride, NaCl.This force enables the two ions to stick together through ionic bond.
8.By using example,describe the formation of covalent bond between element from Group 14 and element from Group 17.
-Example of formation:tetrachloromethane,CCl4
(Carbon-G14;Chlorine-G17)
-The formula of tetrachloromethane molecule is CCL4.Carbon is in group 14 of the periodic table.It has
four electron in its valence shell.In order to achieve the octet electron arrangement,each carbon atom needs another four more electrons to form an octet electron arrangement.
-Chlorine atom is in group 17 of the periodic table.It has 7 valence electron.It needs one more electron to achieve the octet electron arrangement.
-When one carbon atom share one electron with four chlorine atom,both carbon atom and chlorine atom can achieve a stable electron arrangement.This means that each chlorine atom share pair of electron with a carbon atom.This indicates single covalent bond.
9.Draw electron arrangement of the compound formed from the following elements.
b)Carbon and oxygen c)Magnesium and chlorine d)Carbon and hydrogen e)Hydrogen and chlorine f)Sodium and oxygen
1.State the meaning of electrolyte -Substances that can conduct electricity when they are in molten or aqueous solution and undergoes chemical changes.
2.State the meaning of electrolysis -A process whereby compounds in molten or aqueous solution are broken down into constituent element by passing electricity through them.
3.State three factors affecting electrolysis of an aqueous solution
-Position of ions in the electrochemical series -Concentration of ions in the electrolytes -Types of electrodes used in the electrolysis 1)Inert(Carbon/Platinum)
2)Active(Copper,etc.) 4.explain why solution of hydrogen
chloride in water can conduct electricity but solution of hydrogen chloride in methylbenzene cannot conduct electricity?
Hydrogen
chloride in water
Aspects Hydrogen chloride in
methylbenzene Yes Conduct electricity No This is because in water,hydrogen chloride is in the form of ions as it has dissociated.The hydrogen ion and chloride ion present in the aqueousbsolution carries positive and negative charges repectively.These charges are able to move
freely.Hence,it is able to conduct electricity.
Inference This is because in
methylbenzene,hydrogen chloride exists as neutral molecules.It has no charge.Hence,it is unable to conduct electricity.
5.By using example,explain how the following factors can determine the selective discharge of ions at the electrodes.
a)types of electrodes b)concentration of the ions 6.Describe the electrolysis of the molten lead()bromide
1.A crucible is filled with solid lead()bromide PbBr2 until it
2.The apparatus are set up as shown.
3.The solid lead()bromide,PbBr2 is heated util it is
completely molten.
4.The circuit is switched on for about 20 minutes.The changes at the anode and the cathode are observed. 5.The circuit is switched off and both electrodes are taken out from the electrolyte.The molten lead()bromide is carefully poured into a beaker.
6.What is left at the bottom of the crucible is observed and recorded.
7.Describe the extraction of aluminium by electrolysis
1.Cryolite,Na2AlF6 is added to aluminium oxide to lower the
melting point to about 8500C. 2.The electrodes are made graphite.
3.In the molten state,aluminium oxide will dissociate to aluminum ions and oxygen ions according to the folloeing equation:
Al2O3 2Al3++3O
2-4.At the cathode: 4Al3++12e- 4Al At the cathode: 6O2- 3O2 +12e
Overall Equation:4Al3+ + O2- 4Al + 3O2
5.Oxygen will be formed at the anode.It will burn the graphite electrode to form carbon dioxide.Hence,the graphite anode needs to be replaced occasionally. 6.The aluminium is siphohed off as molten aluminium. 8.Draw the structure of Daniel Cell and
explain how it can produce electricity
1.The solutions are connected through a salt bridge and porous pot
Negative terminal Positive terminal
Zinc Copper
Zinc metal becomes thinner because zinc atom from the electrode loses two
electrons to form zinc ion.Zinc electrode dissolved.
Copper metal becomes thicker because the copper(ll) ions in the copper (ll) sulphate solution receive two electrons to form copper atoms which are later deposited at the copper electrode.
Overal ionic equation:Zn + Cu2+ + Cu
The flow electrons from the zinc electrodes to the copper electrode results in the flow of alectrical current and thus produces electricity.
9.Draw the structure of a dry cell and
explain how it can produce electricity Negative terminal Positive terminal
Zinc Carbon
Zinc metal releases electrons and dissolves to form zinc ions.
Ammonium ions receive electrons to produce ammnia gas and hydrogen gas
Zn Zn2+ + 2e- 2NH4+ + 2e- 2NH3 + H2
1.Manganese(lV)oxide,MNO2 oxidises the hydrogen gas and
minimizes the formation of gas bubbles at the carbon rod when the cell is in use
2MnO2 + H2 Mn2O3 + H2O
2.The flow of electrons from the zinc metal casing (the external circuit) to the carbon rod results in the flow of electrical current and thus produces electricity.
10.Describe a laboratory experiment to extract lead from lead()oxide by using electrolysis
Anode Cathode
2O2- O2 + 4e- Pb2+ + 2e- Pb
Overall ionic equation: 2Pb2+ + 2O2- 2Pb + O2
11.Describe a laboratory experiment to show that types of electrodes affecting the selective discharge of ions in electrolysis of copper()sulphate solution.
12.You are given magnesium ribbon ,copper plate,magnesium nitrate solution ,copper()sulphate solution,connecting wires with crocodile clips,250cm3
beaker,voltmeter and porous
pot.Construct a voltaic cell by using the above materials
Explain how the voltaic cell can produce electricity.Your answer must include observation and half equetions for
reaction at anode and cathode
13.Describe a laboratory experiment to construct the electromechanical series of magnesium,copper,zinc and lead
1.State the meaning of acid and alkali Acid -Chemical substances which ionizes in water to produce hydrogen ions,H+
Alkali-Soluble base 2.What is the meaning of strong acid
and weak alkali
Strong acid-Acid which ionizes completely with water to form hydrogen ion,H+(HCl)
Weak Alkali-Alkali which partially ionizes in water to form hydroxide ion,OH-(NH3)
3.What is neutralization? -Reaction of an acid and a base
4.What is salt? -A compound formed when the hydrogen ion,H+ from an acid is replaced by ametal ion or an ammonium ion. 5.What is precipitate reaction? -The method used to prepare insoluble salt where two
soluble salt solutions are mixed together. 6.The pH value of ammonia in water is
9 but the pH value of solution of
ammonia in trichlomethane is 7.Explain why pH value of two solutions is
different Ammonia in water Aspects Ammonia in trichlomethane 9(alkaline) pH 7(neutral) This is because ammonia partially dissociates in water to form hydroxide ions.The presence of hydroxide ions causes the pH value to increase
Inference This is because ammonia exists as neutral molecules in trichlomethane.There is no presenc of either hydrogen ion or hydroxide ion that will change the pH value.Thus it is neutral.
7.80cm3 if distilled water is added to 20cm3 of 2.0 mol dm-3 solution of HCl.Find the molarity of the dilute solution.
M1V1=M2V2
2.0moldm-3(20/100dm3)=M2(100/100dm3)
M2=0.4moldm-3
8.In titration ,40cm3 of 0.25 mol dm-3 potassium hydroxide,KOH solution is needed to neutralize 20cm3 of nitric acid,HNO3.Calculate the molarity of the
nitric acid,HNO3
KOH + HNO3 KNO3 + H2O
MaVa = a
MbVb b
0.25(40) = 1 M(20) 1
9.Given dilute nitric acid and dilute sulphuric acid have the same concentration of 0.5 mol dm-3.In neutralization experiment,20 cm3 of nitric acid is required to neutralize 20cm3 of sodium hydroxide solution but only 10cm3of sulphuric acid is required to neutralize 20cm3 of sodium
hydroxide solution.Explain why.
-Sulphuric acid is a diprotic acid,when it dissociates in water to produce two hydrogen ions per mole
-Nitric acid is a monoprotic acid,each of it dissociates to form one hydrogen ion.
-Thus though same molarity of both acids are used to neutralize the same amount of acid with the same molarity,higher volume of nitric acid would be used as compared to the volume of sulphuric acid used because it nitric acid has half the number of hydrogen ion as compared to sulphuric acid.
10.Describe a chemical test to determine a given solution is an acid solution
11.Describe a laboratory experiment to determine the concentration of sodium hydroxide by using titration process.You are given 0.2 mol dm-3 of dilute
sulphuric
acid,phenolphthalein,burette,pipette and conical flask
12.You are given solid sodium chloride.Describe how to prepare sodium chloride solution of 0.2 mol dm-3 in laboratory by using 250cm3 volumetric flask.
13.Describe the preparation of zinc sulphate
14.Describe the preparation of lead()chloride
15.Describe the preparation of potassium nitrate
16.Solid W is a salt.Describe the tests you would carry out to confirm the presence of zinc ions and nitrate ions in the salt?
17.Solid X is a metal carbonate.Describe the test you would carry out to confirm that X consists of carbonate ions
besides heating.
18.You are given four test tubes filled with the solution consists of zinc ions,lead()ions,aluminium ions and
magnesium ions respectively.Describe the tests you would carry out to confirm the ion that present in each test tube.
19.You are given potassium chloride solution,lead()oxide powder and dilute nitric acid.Describe how you would prepare lead ()chloride salt from the given materials.
20.You are given diluye sulphuric acid,copper()nitrate solution and sodium carbonate solution.Describe how you would prepare
copper()sulphate salt from given materials.
1.What is the meaning of alloy? State the aims of making alloys
-A mixture of 2 or more elements with a certain fixed composition in which the major component is metal(elements combined phusically)
2.What is the meaning of composite materials? State the components of the following composite materials: a)Reinforced concrete b)superconductor c)Fibre optic d)Fibre glass e)Photochromic glass
-A structural material that is formed bu combining two or more different substances such as metal,alloys,ceramics,glass and polymers.
Composite materials
Components Reinforcement
Concrete
Steel bars and
concrete(cement,sand and small pebbles) Superconductor Yattrium
oxide,barium
carbonate,copper(II) oxide
Fibre Optics Silica,sodium carbonate,calcium oxide
Fibre Glass Glass fibre and polyster(a type of plastic)
Photochromic Glass
Glass and silver chloride or silver bromide
3.State the
catalyst,temperature and pressure of the following process: a)Contact process b)Haber process
Process Catalyst Temperature Pressure Production Haber Process Iron 400-4500C 150-300atp Ammonia Contact Process Vanadium(v) oxide,V2O5 5000C 1-21tp Sulphuric acid 4.What is the meaning of polymers?
Name the monomer of polythene and polyvinyl chloride
-Large molecules made up of many identical repeating sub-unit called monomers which are joined together by covalent bond
Monomer Synthetic Polymer
Ethene Polythene
Chloroethene Polyvinyl chloride,PVC
5.State four types of glass and their compositions.List the uses of each glass.
Type of Glass
Coponents Characteristics Uses Soda-lime Glass Silicon oxide,sodium oxide,calcium oxide Good chemical durability,high thermal expansion coefficient,easy to make into different shapes,low melting point Bottles,window panels,mirror,bulbs,flat galss,glass containers Lead Crystal Glass Silicon oxide,sodium oxide,lead oxide,potassium oxide,aluminium oxide
Soft and easy to melt,high density,high refractive index Art objects,lens,prism,chandeliers Borsilicate Glass Silicon oxide,sodium oxide,calcium oxide,Boron oxide,aluminium oxide Low thermal expansion coefficient,resistant to heat and chemical attact Cooking utensils,lab glassware,automobile headlights Fused Glass
Silicon oxide High heat resistant,high transparency,high melting point,resistant to chemical attact Lab glassware,lenses,telescope,mirrors
6.What is
ceramics?State the properties and list the uses of ceramics.
-Made from clay,such as kaolin.
Properties Uses
Strong and hard Building materials
Rust proof and chemicall resistance Kitchen ware
High melting point Heat insulator
Longer lasting and pleasing Decorative items
Hard and not compressible Dental and medical uses Electric insulators Electrical items
7.Bronze is an alloy consists of copper and tin.Explain why bronze is harder than copper.
Bronze Copper
Tin atoms are added to the copper atoms arrangement.Tin atoms are bigger than copper atoms.As a result,the uniformity of the arrangement of copper atoms is disrupted and this prevents the layers of copper atoms to slide aver one another. This made bronze harder than pure copper.
Copper atoms are arranged in an orderly manner and are packed close
together.Because the copper atoms are all in the same size,it enables the layer of copper atoms to slide over easily when a force is applied.
This shows that pure copper is malleable and soft
8.Explain how acid rain is formed. Describe how acid rain causes
environmental pollution.
Acid Rain:
1.Release of of sulphuric dioxide from chimney of factories,and the burning of petrol in cars.
2.The wind carries the pollutant around the globe. 3.Formation of acid rain:
a)Sulphur dioxide in air reacts with water and oxygen to form acid rain. Effects:
a)Acid rain coorodes buildings and metal structures. b)Flows into rivers and lakes causing water pollution. i)Lakes and rivers become acidic
ii)Fish and other organism die c)Acid rain destroys trees in forest d)Causes soil pollution
i)pH of the soil decreases
ii)salts are leached out of the top soil iii)roots of trees are destroyed
iv)plants die of malnutrition and diseases 9.Explain the
industrial process
involved in the manufacture of sulphuric acid.Write all the chemical equations involve.
Steps involved:
1.Sulphur is burnt in a furnace together with dry air to produce sulphur dioxide. S + O2 → SO2
2.Sulphur dioxide and air are passed over a converter to be converter to sulphur trioxide with the presence of:
a)Catalytst:Vanadium(V)oxide,V2O5
b)Temperature:450-5000C c)Pressure:2-3 atp
2SO2 + O2 2SO3
3.Sulphur trioxide is dissolved in concentrated sulphuric acid to form a product called
oleum.
SO3 + H2SO4 H2S2O7
4.Water is added to oleum to produce concentrated sulphuric acid H2S2O7 + H2O 2H2SO4 10.Explain the industrial process involved in the manufacture of ammonia gas.Write all the chemical equations involve.
Process named:Haber process Steps involved:
1.Nitrogen gas and hydrogen are mixed and scrubbed to get rid of impurities.
2.One volume of nitrogen gas and three volume of hydrogen gas are compressed in the presence of 150-300 atp.
N2 + H2 2NH3
3.Then,it goes to the converter.The conditions are: a)Catalyst:Iron
b)Temperature:400-4500C
4.The mixture of gas leaves the converter and is cooled until ammonia condense.Only 10% of the mixture will produce ammonia.
5.The rest of the unsuccessful nitrogen and hydrogen gas are then pumpedback to the converter for another chance to react.
6.The ammonia formed are then liquefied and separated to get a better yield.It is then stored under pressure tanks,
11.Describe a laboratory experiment to prepare ammonium sulphate(ammonium fertilizer) 12.Describe a laboratory experiment to compare the hardness of brass and copper.
