END OF TOPIC QUESTIONS.

1. i. Explain how a sample of nitrogen can be isolated from air

ii. Ammonia is manufactured by water process. Name the best conduct for this process, and state 2 uses of ammonia

2. Explain how nitrogen can be prepared in laboratory

3. Explain the observation made.

1. Brown former are observed when NO is exposed to air

2. Nitric acid is stored in dark brown bottles

3. Nitric acid is often yellow.

4. Given NH₄(SO₄)₂ and NH₄NO₃ Which one would you say is the best fertilizer? Show your working

Calculate the volume of oxygen produced when 20g KNO₃ is is decomposed. Molar gas vol at composed. Molar gas vol at stp = 22.4 liter

5. Using equation show and name reagent used to make

1. Nitrogen

2. nitrogen oxide

3. Nitrogen dioxide gases in laboratory

6. When a small burning Magnesium ribon was lowered into jar nitrogen dioxide, a white powder was product and brown colour disappeared. Suggest explain for the observation

b . The equation below is for manufacture of ammonium by Haber process

N_{2 (g) +} 3H_{2 (g)} 2NH₃ ?H = -Ve

1. In term of reacting volume what is the best pressure for the reaction above.

2. Does it require high or the low temperature?

7. State how the oxidation of ammonia gas by burning in oxygen differs from it catalytic uses platinum as the catalyst.

8. The set up below shows the preparation of nitrogen gas. Study it and answer questions that follows.

1. State the purpose of sodium hydroxide

2. Write down an equation that shows the reaction taking place in the round bottomed flask

3. With the aid of an equation, explain what takes place in the combustion tubes.

4. The nitrogen obtained using this is not pure. Explain why this is so

9. During the haber process of the manufacture of ammonia, hydrogen and nitrogen rreact according to the equation show below.

N_{2 +} 3H_{2 ?} 2NH_2(g) (H = -92Kj)

1. Name the catalyst used in above process.

2. Calculate how much energy would be envolved it 10g of hydrogen is used (H = 1.0).

SAMPLE NECTA QUESTIONS.

3. (a) Write ionic equations for the following:

1. Laboratory preparation of ammonia gas.

2. Precipitation of barium sulphate from barium chloride and sodium sulphate and silver chloride from a soluble chloride.

3. Neutralization of a strong acid and a strong alkali.

2007.

QN5 © (c) What will happen when:

1. yellow flowers are introduced into a gas containing chlorine gas?

2. a burning splint is introduced into a gas jar containing hydrogen gas?

3. a glass rod which was dipped in concentrated hydrochloric acid is introduced into a gas jar containing ammonia gas?

4. sulphur dioxide gas is bubbled through a yellow acidified potassium dichromate solution?

2009.

QN. 11.The preparation of ammonia in the laboratory is done by heating a mixture of ammonium chloride and sodium hydroxide.

(a) (i) Write a balanced chemical equation for the above reaction.

(ii) Using balanced chemical equations, state how ammonia reacts with hydrogen chloride gas and heated copper (II) oxide.

(b) (1) State two uses of ammonia.

(ii) Name the catalyst used in the preparation of ammonia.

(c) Explain each of the following reactions, giving observations and equations.

1. Aqueous ammonia is added to iron (III) chloride, little by little, until in excess.

2. Sodium nitrate is strongly heated.

QNS. 8. (a) Ammonia gas can be prepared by heating an ammonium salt with an alkali.

1. Name the most common pair of reagents suitable for this reaction.

2. Write the equation for the reaction.

(b) Ammonia is very soluble in water and less dense than air. How does each of the properties determine the way in which ammonia is collected in a gas jar?

(c) Give reasons for the following:

1. A solution of chlorine in water is acidic.

2. Yellow phosphorus is stored under water.

SULPHUR AND ITS COMPOUNDS.

OCCURRENCE.

Sulphur occurs in form of mineral compounds such as

• Pyrite- Fes

• Gypsum – CaSO₄-2H₂O

• Mirabilite- Na₂SO₄.10H₂O.

Sulphur is also a constituent of plant and animal protein. Elemental Sulphur is not toxic to humans but it has fungicidal effects.

Pure Sulphur is fragile, crystallined, yellow in color, with several allotropic modifications. These allotropes include, rhombic, monoclinic, plastic, and prismatic.

Sulphur occur in rings called Sulphur 8 rings.

Extraction of Sulphur.

Sulphur is obtained from underground by a process called frasch process. The Sulphur is found about 200m underground. Three concentric rings are erected downward to the molten Sulphur. Super heated water at 170^oC, IS passed through outer pipe, where it melts the hot Sulphur. Hot air is passed at 16atm, through middle pipe and helps in making the Sulphur molten. Because of the pressure of the build inside; molten Sulphur is passed through middle ring (pipe) and is collected in a reservoir.

Diagram.

Figure 1.6 Frasch process

Allotropes of Sulphur.

Sulphur exists in two main allotropes,

Rhombic and monoclinic

Other allotropes includes plastic and amorphous Sulphur.

Rhombic Sulphur.

Also called alpha Sulphur or octahedral Sulphur due to the shape of its crystals. It is formed when Sulphur is dissolved in warm methyl benzene. The shape of rhombic Sulphur is as shown below.

Figure 1.7 Rhombic sulphur

rhombic Sulphur is stable below 96^oc.

Monoclinic Sulphur.

It is also called prismatic Sulphur or beta Sulphur. It is formed when Sulphur is heated slowly on evaporating dish until it melts. Monoclinic Sulphur is stable above 96⁰C.

Figure 1.8 monoclinic sulphur

Plastic Sulphur.

Formed when molten Sulphur is gradually poured in a beaker of cold water. At room temperature plastic Sulphur gradually changes into rhombic Sulphur.

The temperature of 96⁰C, above which monoclic Sulphur is formed and below which rhombic sulphur is formed is called transition temperature.

Figure 1.9 Transition between the two allotropes

Effects of heat on Sulphur.

• At 119^oC, SULPHUR melts to give a yellow liquid whose viscousity decreases until 155⁰C. This is because of breaking S-S rings.

• On further heating, viscosity increases, upto 159^oc due to opening of S8 rings

• Above 200^Oc, viscosity with the liquid eventually acquiring a more reddish hue at high temperature. This is caused by thermal breaking of Sulphur chains

• The liquid boils at 444oc to form a reddish brown vapour.

Properties of Sulphur.

1. Combustion

Burns in plenty of air to from Sulphur dioxide, in air enriched with oxygen, it burns to form Sulphur trioxide.

S _(s) + 0_2(g) ?SO_2(g)

2S_(s) + O_2(g) ? 2S0_3(g)

Reaction with metal.

Sulphur reacts with iron and copper to form sulphides.

Fe_(s) + S_(s) ? FeS_(s)

Fe_(s) + Cu_(s) ? Cu₂S_(s)

Both iron sulphide and copper sulphide are black in color.

Reaction with non metal

With cabon, Sulphur combines to from carbon disulphide which is very poisonous.

C_s + S _s CS_{2 g}

Reactions with acids.

With nitric acid, sulphuric acid is formed and the nitric acid is reduced to brown nitrogen IV Oxide.

S_(s) + 6HNO_3(aq) ? H₂SO₄ + NO₂ + 2H₂O

Concentrated sulphuric acid oxidizes Sulphur into Sulphur dioxide and water.

H₂SO_4(l) + S _(s) ? 3S0_2(g) + 2 H₂O_(l).

Hydrochloric acid does not behave the same way because it is not an oxiziding agent.

Uses of Sulphur.

• As a fungicide in dusting of vines

• Manufacture of sulphuric acid in contact process

• Vulcanization or hardening of rubber

• Making bleaching agents in the paper industry

• Manufacture of fire works, dyes and Sulphur compounds.

The contact process.

This is the industrial manufacture of sulphuric acid. The process involves four stages which are;

1. Preparation of Sulphur IV Oxide

2. Purification of Sulphur IV oxide

3. Conversion of Sulphur IV Oxide into Suphur VI Oxide.

4. Conversion of Sulphur (VI) Oxide into sulphuric VI acid.

1. Preparation of Sulphur IV Oxide

Formed by burning Sulphur in air or burning Sulphur ores in air.

• S_(s) + O _2(g) ? SO_2(g)

• 2Fe _S(s) + O _2(g) ? SO_{2 (g)}

Other sulphides such as zinc, copper, can be used instead of iron.

2. Purification of Sulphur (IV) Oxide

The mixture of Sulphur(IV) Oxide and excess air are purified to remove dust particles which may poison the catalyst.

3. Conversion of Sulphur dioxide into Sulphur trioxide.

This requires a pressure of 2-3atm, temperature of 400-500Oc and a vanadium (V) Catalyst.

This reaction takes place in a catalytic chamber.

2S0_2(g) + O_2(g) 2S0_3(g) heat= -94KJ/mol

4. Conversion of Sulphur (VI) Oxide into sulphuric (VI) Acid.

The Sulphur VI oxide is passed over absorption tower where it reacts with concentrated sulphuric VI Acid to form oleum,

Sulphur(VI) Oxide + Sulphuric (VI) acid? Oleum

SO _3(g) + H₂SO_4(l) ? 2 H₂S₂0 _7(l)

The oleum formed is then diluted with water to give concentrated sulphuric acid. This occurs in dilution chamber

Oleum + water ? Sulphuric (VI) Acid

H₂S₂O _7(l) + H₂O_(l) ? H₂SO_4(l)

DIAGRAM FOR CONTACT PROCESS.

Figure 1.10. The contact process

Chemical properties of concentrated sulphuric acid.

1. Dehydrating property

This is the ability of the acid to remove elements of water, that is hydrogen and oxygen from a compound.

When conc. Sulphuric acid is added to sugar in a bench, the acids removes oxygen and hydrogen leaving a black mass of carbon.

C₁₂H₂₂0_{11(s) } 12C + 11H₂0

Crystals of blue copper II Sulphate turns white when Conc-sulphuric acid is added.

CUSO₄.5H₂O(s) _ CuSO _4(s) + 5H₂0_(l)

2. Drying agent

The acid is hygroscopic, it absorbs water from the atmosphere and it becomes diluted. When left in open, the volume of the sulphuric acid is found to have increased.

3. Oxidizing power of Conc Sulphuric acid.

It oxidizes zinc and copper to form their salts. Sulphur dioxide gas is also liberated.

Cu_(s) + H₂SO_4(l) ? CuSO_4(aq) + 2H₂O_(l) + SO_2(g)

Zn_(s) + H₂SO_4(l) ?ZnSO_4(aq) + 2H₂O_(l) + SO_2(g)

The acid oxidizes non-metals to their 0xides

C(s) + H₂S0_4(l) ? CO_2(g) + S0 _2(g) + H₂0_(l)

S(s) + H₂S0_4(l) ? S0_2(g) +2 H₂0_(l)

Dilute Sulphuric acid.

1. Reaction with metals

It reacts with metals above hydrogen liberating hydrogen gas. For very reactive metal, the reaction is very dangerous and should not be tried.

The reactivity decreases as one moves down the reactivity series.

Eg. Mg _(s) + H₂S0_4(aq) ? MgSO_4(ag) + H_2(g)

Reaction with carbonate and hydrogen carbonate.

The product of this reaction is carbon dioxide salt and water. The presence of carbon dioxide can be confirmed by use of lime water where it turns into white precipitate.

The reaction between calcium and lead with sulphuric acid stops after a certain period of timw due to formation of insoluble salts.

Na2CO_3(s) + H₂SO_4(aq) ?Na₂SO_4(aq) + CO_2(g) + H₂0_(l)

ZnCO_3(s) + H₂SO_4(aq) ?ZnSO_4(aq) + CO_2(g) + H₂0_(l)

CuCO _3(s) + H₂SO_4(aq) ?CuSO_4(aq) + CO_2(g) + H₂0_(l)

Reaction with hydroxides of metals.

It produces salts and water with hydroxides and metal oxides, this is called neutralization.

Copper oxide reacts with dilute sulphuric acid to form a blue solution of copper II Sulphate.

CuO(s) + H₂SO_4(aq) ?CuSO_4(aq) + H₂0_(l)

With copper hydroxide,

Cu(OH)_2(s) + H₂SO_4(aq) ?CuSO₄ + H₂O

USES OF SULPHURIC ACID

Sulphuric acid is used in the following ways.

• Manufacture of fertilizers

• Making synthetic fibres

• In refining petroleum

• Petro chemicals and dye stuffs

• Pigments of paints

• In metallurgy sulphuric acid is used in extraction of metals

• In car batteries and accumulators

• As drying agents for gases

• In pickling; cleaning of metal surfaces

• In the manufacture of soaps and detergents.

Sulphur (IV) Oxide.

This gas is prepared in the laboratory by reacting conc. H2SO4 acid and copper metal. The gas is dried over conc. Sulhuric acid and collected by down ward delivery. It has irritating smell and is colorless.

Figure 1.11 Preparation of sulphur dioxide

Properties of Sulphur IV Oxide.

Physical properties.

• It is a colorless gas with an irritating smell.

• It turns damp litmus paper blue and then bleaches it.

• It is denser than air

• It is readly soluble in water forming sulphorous acid.

Chemical properties.

1. The gas neutralizes alkalis such as sodium hydroxide forming sodium hydrogen sulphite and water.

NaOH_(aq) + SO_2(g) ? NaHSO_3(aq),

When the alkali is in excess, a sulphite is formed

2NaOH_(aq) + SO_2(g) ?Na₂SO_3(aq) + H₂O_(l)

2. Reducing property.

1. Sulphur dioxide reduces dichromate ions into chromium (III) Ions. This is the test for Sulphur dioxide

CrO7^2- (aq) + 3SO_2(g) + 2H+(aq) ?2Cr³⁺⁽aq) +3SO4^2- + H₂O_(l)

2. SO₂ reduces acidified purple manganite (VII) ions, MnO₄ to Colorless manganese (II) ion, (Mn²⁺). SO₂ Itself being oxidized to sulphuric (VI) acid.

2MnO^-4(aq)+5S0_2(g) +2H₂O_(l) ?2Mn²⁺ (aq)+5SO^2- +4H⁺(aq).

3. Bleaching property.

Sulphurous acid bleaches by reduction, in which it supplies oxygen to the dye.

SO_2(g) + H₂0_(l) ?H₂SO_3(aq)

H₂SO_3(aq) + ( dye +O) ? H₂SO4_(aq) + dye- colorless

4. Oxidizing property.

• Sulphur dioxide oxidizes hydrogen sulphide into Sulphur and water.

• SO₂ + 2H₂S(g) ?3S(s) + 2H₂O (l)

• A yellow deposit of Sulphur is formed.

• It oxidizes magnesium into magnesium oxide and is itself reduced into Sulphur.

Mg_(s) + SO_2(g) ?2MgO_(s) + S_(s)

Uses of sulphur IV Oxide.

1. For fumigation to kill insect pest because the gas is poisonous

2. For leaching straws, sponges, paper and silk

3. Preservation of fruit juices and other food stuffs

4. Used as intermediate compound in manufacture of sulphuric acid in contact process

Effects of sulphuric acid

Accumulation of sulphuric acid in the atmosphere can lead to;

1. Formation of acid rain which affects animals and plants

2. Irritation of throat and eyes due to exposure, if inhaled, it can cause infection of respiratory system

3. Acid rain interferes with the PH of soil thus affecting plant growth.

SUMMARY

• Sulphur is a non metal in group (IV) of periodic table it is found in Lousiana and Texas in USA in free from and also in force from and also in performance genes eq at , france are hydrogen sulphide

• Sulphur is extracted by frasch process

• Sulphur occur in two allotropic forms rhombic with octahedral shape and stable above 96⁰C and monoclinic sulphur which is stable above 96⁰C it is prismatic.

• Sulphur is yellow in colour and has a variety of use in manufacture of sulphuric acid, fungicides, bleaching agents etc.

• When heated Sulphur, behaves very intresting changing in viscousing till it boils at 444⁰C.

• Hydrogen sulphide Is a strong reducing agent

• Sulphur has two oxide, Sulphur dioxide and Trioxide. Sulphur dioxide is prepared by reactions of Conc. Sulphuric acid on copper.

• Conc.sulphuric acid is an oxidizing agent dehydrating agent and hydroscope

• The acid can displace more volatile acid from their salts

• Sulphur (IV) oxide has pollution effect on the environment.

END OF TOPIC QUESTIONS

1. Name two sources of sulphur

2. Explain how frasch process works in extracting sulphur

3. Name two allotropes of Sulphur

1. Briefly explain what happens when Sulphur is heated till foils. Draw a graph showing the changes of discoursing as temperature increase.

2. Jane is given two solutions, suspected to be Sulphite and Sulphates. Describes how she can differentiate the two

4. Explain why

1. During contact process Sulphur Trioxide is dissolved in sulphuric acid and not water

2. A temperature of 450⁰C is used in contact process although the process require low temperature?

3. You should not add water to acid sulphuric acid.

5. The reaction between sulphurdioxiede and nitric acid is as follows

SO_{2(g) +} 2HNO_{3(g) ?} H₂SO_{4(g) +} 2NO_2(g)

Identify

Reducing agent

Oxidizing agent

Between SO₂ and HNO₃ Which is strong reducing agent.

10. The diagram below illustrates the extraction of sulphur in the Frasch process.

Name the pipe through which heated water is pumped.

11. The equation below shows how sulphur (IV) oxide is converted to sulphur (VI) oxide.

2SO_{2(g) +} O_{2(g) ?} 2SO_3(g) (?H = -196Kj)

2. Name one catalyst used for this reaction

3. State and explain the effect on the yield of sulphur (VI) oxide when:

1. The temperature is increased

2. The volume of oxygen used in increased.

6. Explain what happen when,

1. Acidified potassium dichromate (vi) is reacted with sulphuric (iv) oxide wite equation for reaction.

2. Concentrated sulphuric acid is poted in sugar on bench

7. Stating from sulphur, describe how you can prepare

1. Plastic sulphur

2. Sulphur dioxide

3. Hydrogen sulphide

4. Hydrogen sulphide

8. Complete this equations

H₂S_{(g) +} O₂ ? ?

H₂S_{(g) +} O_2??

9. Describe an experiment which can be used to show that Sulphuric acid is hygroscopic

10. Explain why paper turn brown after being exposed to sunlight for long time.

b. how do bleaching agent of chlorine and Sulphur dioxide differ?

c. which is the best bleaching agent.

11. Explain two ways which can be used to show a gas is Sulphur (IV) Oxide

12. When a sample of concentrated sulphuric acid is left in an open beaker in the laboratory for two days, its volume is found to have increased.

1. State the property of the concentrated acid that is shown by this observation

2. State one use of concentrated sulphuric acid that depends on the property in a above

3. Using an equation explain how sulphur (IV) oxide bleaches substances.

4. Name the catalyst preferred in the contact process of manufacturing sulphuric acid and explain why it is preferred.

SAMPLE NECTA QUESTIONS.

2015

4. (a) Briefly explain what will happen when:

1. concentrated sulphuric acid is exposed to the atmosphere.

2. iron (II) sulphate is exposed to air for a long time.

3. a bottle containing AgNO₃ is left open.

(b) Give three applications of the process of neutralization in daily life.

CARBON

Carbon exists mostly in free state as graphite and diamond. It exists in a number of forms such as wood charcoal, animal charcoal, coke and soot or lamb black. It occurs in many substances eg, carbon dioxide, carbonate, shells, and in all organic matter.

Allotropes of carbon.

Allotropy is the existence of an element in more than one form in the same physical state.

Allotropes- are different forms of an element with different physical properties but the same chemical properties.

Allotropes of carbon.

• Diamond

• Graphite

• Amorphous

Diamond and graphite are crystallized forms while amorphous is non-crystallized form.

Diamond

Diamond is the hardest substance known on earth. In diamond, each carbon is joined by covalent bond to four other carbon atoms. This forms a tetrahedral structure. The forces that bond the atoms are equally strong in all directions in diamond. Compared to graphite, diamond is more denser because its atoms are closely packed. Diamond has no free electrons and hence it is an insulator meaning it does not conduct electricity.

Figure 1.12. Diamond structure

Physical properties of diamond.

• Has high melting and boiling point due to strong covalent bonds.

• It is a bad conductor of heat and electricity

• It is colourless, transparent and sparkling

Uses of diamond.

1. Because of high refractive index, it is used as a gemstone or valuable stone

2. For cutting glass, drilling of rocks, and for abrasive purposes because of its hardness

3. Used to make jewellery, such as rings, because of its shiny and attractive appearance

Graphite.

In graphite, only three out of four electrons in carbon are used in bonding. One electron is thus left to move free. For this reason, graphite is able to conduct electricity

The arrangement of atoms in graphite forms hexagonal rings of six carbon atoms. The hexagonal layers are joined by weak covalent bonds-allowing them to slide over each other.

Figure 1.13. Graphite structure

Physical properties of graphite.

1. Due to delocalized electrons, it is a good conductor of electricity

2. It is soft and slippery because of weak van der waal forces

3. Has high melting and boiling point because of presence of strong electrovalent bonds.

Uses Of Graphite.

1. It is mixed with clay to make lead pencils.

2. Used as an electrode in electrolytic cell because it is very innert

3. Used as a lubricant because of its greasy and slippery property

Amorphous carbon.

Is a non crystallined form of carbon. The arrangement of atoms are disorderly. This allotrope does not occur naturally but exists in various forms.

• Charcoal

• Coke

• Lampblack

1. Charcoal.

Charcoal exists in three main forms, animal charcoal, suagar charcoal and wood charcoal.

Animal charcoal

Formed when bones are heated in limited supply of air. It is used to whiten crude sugar by removing the brown impurities.

Sugar charcoal

It is formed by destructive distillation of sugarcane. Also formed when conc. Sulphuric acid dehydrates sugar. This charcoal is used to absorb gases in chemical processes.

Wood charcoal

Formed by destructive distillation of wood. It is used as gas masks because it absorbs poisonous gases

2. Coke.

Is formed when coal is heated in absence of air.

Uses of coke.

• Used as a fuel in furnaces, boilers and ovens

• It is used as a reducing agent in the extraction of metals

• Used as a source of gaseous fuel

3. Lamb black.

They are formed when petroleum, kerosene, turpentine, and natural gas and other hydro-carbons are burnt in limited supply of air.

Uses of lamb black.

1. Making Indian ink, black shoe polish, carbon paper, and printers ink.

2. In making rubber tyres, which makes the rubber strong.

Reducing properties of carbon.

Carbon is a reducing agent.

1. It reduces the oxides of metals to their respective metals and carbon dioxide

Lead (II) Oxide + Carbon? lead + carbon dioxide

Copper(II) Oxide + Carbon?copper + Carbon IV Oxide.

2. Carbon also reduces hot nitric V acid to nitrogen (IV) oxide (NO2), and hot suphuric acid to Sulphur IV acid respectively.

Carbon + Sulphuric Acid?carbon dioxide + Sulphur dioxide + water

Carbon + nitric acid?carbon dioxide + nitrogen IV Oxide + Water

Carbon (IV) Oxide.

Occurrence.

It occurs in the atmosphere where it occupies 0.03%. it is also a constituent of bodies of plants and animals.

Preparations.

It is prepared by reacting dilute hydrochloric acid with marble chips- calcium carbonate.

Figure 1.13. Preparation of carbon dioxide

The dilute hydrochloric acid reacts with the carbonate forming effervescence with evolution of carbon dioxide.

Calcium carbonate + hydrochloric acid ? calcium chloride + carbon (V) Oxide

CaCO₃(s) + 2HCl_(aq) ?CaCl_{2 (aq)} + C02_(g) + H₂0 (l)

Physical properties of carbon dioxide.

• It is colourless, odourless gas with a faint acid taste

• It is soluble in water forming carbonic acid

• It is heavier, than air.

Chemical properties.

1. The gas does not support combustion

2. Dissolves in water forming weak carbonic acid

3. It reacts with alkalis to form carbonates

4. Carbon dioxide can react with burning magnesium. When burning magnesium is introduced in a gas jar fully of carbon dioxide, it continues to burn oxidizing the magnesium into magnesium oxide while itself is reduced to carbon. The heat produced by burning magnesium decomposes carbon IV Oxide to carbon and oxygen.

The oxygen reacts with magnesium.

Uses of carbon (IV) Oxide

1. Used as fire extinguisher because it does not support combustion

2. Use to make fizzy drinks

3. Used as a refrigerant

4. Used in baking bread and coke.

5. In fruit preservation, by creating an atmosphere in which there is less oxygen and more carbon dioxide.

Test for carbon dioxide

This gas is tested by passing through lime water in which the lime water changes into white precipitate.

The formation of white precipitate is due to the presence of solid calcium carbonate

Ca(OH)_2aq + CO_2(g) ?CaCO_3(s) + H₂O (l)

When excess carbon dioxide is passed, the solution turns into colourless due to formation of soluble calcium hydrogen carbonate.

NON METALS AND THEIR COMPOUNDS

• Non metals react by gaining electrons; they are electronegative.

• Electro negativity is the tendency of a non metal to gain electrons.

• Non metals displace each other in their aqueous compounds.

• Chlorine bleaches only in the presence of water.

• Chlorine reacts by gaining electrons. it is an oxidizing agent.

• Chlorine gas is a poisonous. It is prepared in a fume cupboard.

• Hydrogen gas is poisonous. It is prepared by the action of concentrated sulphuric (IV) acid on rock salt.

• Hydrogen chloride gas turns wet blue litmus paper red; it has acid properties in solution form.

• Hydrogen chloride gas forms white fumes of ammonia chloride with ammonia gas. This is the test for hydrogen chloride gas

• Sulphur is extracted from natural deposits by the frasch process.

• The main allotropes of sulphur are rhombic, monoclic and plastic sulphur.

• Sulphur exhibits both oxidizing and reducing properties.

• Sulphuric (VI)Acid is manufactured by the contact process.

• Concentrated sulphuric acid (VI) acid is adehyrating agent. It can remove water or elements of water from compounds.

• Sulphur (IV) oxide causesbleaching by reaction.

• Sulphur (IV) oxide reacts as an oxidizing agent with some reagents during which it reduces to sulphur.

• Sulphur (IV) oxide is used as an intermediate in the manufacture of sulphuric (IV) acid.

• Nitrogen gas can be prepared in the laboratory by isolution from air.

• Nitrogen is inert at room temperature due to the strong triple convalent bonds between its atoms.

• Nitrogen is a major raw material in the manufacture of ammonia gas.

• Ammonia is prepared in the laboratory by heating an ammonia salt with a base.

• Ammonia is highly soluble in water and exhibits alkaline properties in solution form,

• Ammonia forms white fumes of ammonium chloride when reacted with hydrogen gas. This is the test for ammonia.

• Carbonate (IV) oxide can be prepared in the laboratory by the action of dilute acids on suitable carbonate.

• Carbonate (IV) oxide forms a white precipitate with calcium hydroxide or barium hydroxide. This is the test for the carbon (IV) Oxide.

• Allotropy is the existence of an element in more than on form but in the same physical state.

NON METALS AND THEIR COMPOUNDS

1. Define allotropy.

2. Name two crystalline allow tropes of carbon.

3. Damp blue and red litmus paper loses their color when put in a jar of chlorine. By use of equations explain.

4. State one major industrial use of hydrogen chloride gas.

5. State the differences between rhombic and monoclicsulphur.

6. Explain what is observed when concentrated sulphuric (IV) Acid is added to :

1. Sugar

2. Hydrated copper (II) sulphate

7. By the use of relevant chemical equations explain how acid rain is formed.

8. State and explain any two uses of nitrogen.

9. Describe the chemical test for ammonia.

TOPICAL EXAMINATIONS

CHEMISTRY FORM FOUR

NON-METALS

SECTION A 20 MARKS.

1. The method of collecting hydrogen chloride gas in a class experiment is known as:

1. Downward displacement of water

2. Downward displacement of air

3. Upward displacement of air

4. Fountain

5. Condensation

2. Which action should be taken immediately after concentrated sulphuric acid is spilled on the skin?

1. It should be rinsed off with large quantities of running water.

2. It should be neutralized with solid CaCO₃.

3. It should be neutralized with concentrated NaOH.

4. The affected area should be wrapped tightly and shown to medical health provider.

5. It should be neutralized with concentrated KOH.

3. The only metal which does not react with dilute hydrochloric acid is:-

1. Magnesium

2. Aluminium

3. Copper

4. Zinc

5. Sodium

4. Which among the following equations correctly shows the reaction between chlorine gas and water?

1. C l_2(g) + H₂0₍₁₎ ? CI_2(g)

B 2C1_2(g) + 2H₂0₍₁₎ ? 4C1^-1_(aq) + 0_2(g) + 2H_2(s)

3. Cl_2(g) + H₂0₍₁₎ ?HCl + HOCI(aq)

4. 2Cl_2(g) + 2H₂0(_I) ?2H0C1 +H_2(g)

5. 2C12(g) + 3H₂0₀₎ ? C1_{2 (.0} + 2H₃0⁺

(v) Which of the following pair of gas can be prepared in the laboratory an: collected over water?

1. Oxygen and Ammonia

2. Hydrogen and Hydrochloric acid

3. Hydrogen and Oxygen

4. Oxygen and Hydrogen chloride

5. Hydrogen and Ammonia

(vi) Two substances are allotropes of carbon if they:

A. both reduce heated iron (III) oxide to iron

B. have different crystalline structure

D. have equal masses

C. have equal shape

E. have the same arrangement of atoms

vii) Which of the following sets of elements is arranged in order of increas­ing electro negativity?

A. Chlorine, fluorine, nitrogen, oxygen, carbon

B. Fluorine, chlorine, oxygen, nitrogen, carbon

3. Carbon, nitrogen, oxygen, chlorine, fluorine

4. Nitrogen, oxygen, carbon, fluorine, chlorine

5. Fluorine, nitrogen, oxygen, chlorine, carbon

viii) The gas formed when dilute nitric acid reacts with magnesium metal is;

1. Nitrogen

2. Hydrogen

3. Oxygen

4. Nitrogen dioxide

ix) which of the following is true about carbon?

1. Carbon dioxide is very acidic

2. Solid carbon d

2. Match the items in list A with the responses in list B by writing the letter of the correct response beside the item number.

List A

List B

Oxygen Sulphur dioxide Ammonia Hydrogen chloride Carbon monoxide Nitrogen Hydrogen Chlorine Nitrogen dioxide Carbon dioxide

Green-yellow gas which rapidly bleaches damp litmus paper. Heats with cracking sound. It rekindles a glowing splint of wood. Colourless gas, extremely poisonous since it combines with haemoglobin in red blood cells. Brown-ring test. Produces a white precipitate of silver chloride in a drop of a solution of silver nitrate. It is the only alkaline gas. Substitution reaction. Explodes with air when a flame is applied. Sweet-aroma smell It is a brown gas. It has very irritating smell and decolorizes potassium manganate (VII) solution with no precipitates left. It turns lime water milky. Colourless, odourless, non-poisonous gas commonly used as a refrigerant. 0. Characteristic yellow flame. Good solvent for fats and grease, non poi­sonous. Blackens lead (II) ethanoate paper. Turns brown on exposure to air. Freezes at 0°C and boils at 100°C. Rotten-egg smell.

3.(a) With the help of chemical equation, what will be observed when ammonia reacts with:

1. Hydrogen chloride?

2. Copper (II) oxide?

(b) It is not advisable to sleep inside a house which is not well ventilated with a burning wooden charcoal. Give a reason for that and write the chemical equation to represent your answer.

4 .(a) The chemical properties of concentrated sulphuric acid can be grouped into oxidizing property and dehydrating property. In which property should sulphuric acid be grouped when it reacts with copper metal? Give reason and write the equation of the reaction.

(b)The preparation of chlorine gas can be represented by the following equation:

Mn0₂ + 4HCI? MnCl₂ + 2H₂0 + Cl₂.

Calculate the number of moles of HCI which are needed to react with 20g of Mn0₂ and list two main chemical properties of chlorine gas.

5. (a) (i) What is the name given to the different forms of the element which exists in the same physical state?

(ii) Carbon exists in two different forms of the same physical state and one of those carbon forms is represented by structure X below. Give the name of the carbon form with structure X.

3. Name the second form of carbon.

4. State one property and one use which depends on the property you have stated for each form of carbon.

5. Carbon can be used to convert copper II oxide to copper as shown in the equation.

C_(S) + 2CuO_(s) ? 2Cu_cs) +CO_2(g)

What is the function of carbon in this equation?

1. Calculate the mass of CuO which can react with 12g of carbon in the equation given in 5 (b) (i) above.

2. What is the effect of carbon monoxide in the blood?

7.(a) Identify the substances by using the following information:

1. A solid is yellow when hot and white when cold.

2. When water is added to a white powder heat is evolved and the white powder changes to blue crystals.

3. An aqueous solution of a greenish crystalline sulphate forms a pale-green precipitate with sodium hydroxide solution which turns to brown on standing and when exposed to air.

4. A colourless gas turns a yellow acidified potassium dichromate paper to green.

5. A colourless gas becomes brown on exposure to air.

(b) With the help of chemical equations explain what happens to the following compounds of ammonia when heated in separate test tubes:

1. A mixture of ammonia chloride and sodium hydroxide solution

2. Ammonium chloride crystals

3. Ammonium nitrate crystals

4. Ammonium sulphate crystals

5. Ammonium nitrite crystals

8. The Diagram below shows the preparation of chlorine gas in a laboratory fume-chamber. Study the diagram and answer the questions that follow.

(a) What do letters A, 8, C, D and E represent?

1. Why is the gas prepared in the fume-chamber?

2. Can the gas be collected over water? Why?

3. What will happen to a damp blue litmus paper if it is introduced into a gas jar full of chlorine gas?

4. What will happen if a gas jar of hydrogen sulphide is inverted over a gas jar of chlorine such that the two gases get mixed? Write a balanced equation for the reaction which will take place between hydrogen sulphide gas and chlorine gas.

(b) (i) List down two uses of chlorine gas.

(ii) Give a balanced chemical equation for the method of preparation of chlorine used in this question.

9. (a) Write ionic equations for the following:

4. Laboratory preparation of ammonia gas.

5. Precipitation of barium sulphate from barium chloride and sodium sulphate and silver chloride from a soluble chloride.

6. Neutralization of a strong acid and a strong alkali.

(b) Consider the following elements of group seven in the order in which they appear in their group in the Periodic Table. F, C, Br, and I.

1. Which element is the most electronegative?

2. Name the least electronegative element.

3. Which element has the largest atom?

4. Write the electronic configuration of the chlorine atom.

(c) Define electro-negativity

11. Which method is used in the laboratory gas preparation of:

1. Ammonia?

2. Chlorine?

3. Hydrogen?

Give reasons for your answers.

(c) What will happen when:

5. yellow flowers are introduced into a gas containing chlorine gas?

6. a burning splint is introduced into a gas jar containing hydrogen gas?

7. a glass rod which was dipped in concentrated hydrochloric acid is introduced into a gas jar containing ammonia gas?

8. sulphur dioxide gas is bubbled through a yellow acidified potassium dichromate solution?

12. The preparation of ammonia in the laboratory is done by heating a mixture of ammonium chloride and sodium hydroxide.

(a) (i) Write a balanced chemical equation for the above reaction.

(ii) Using balanced chemical equations, state how ammonia reacts with hydrogen chloride gas and heated copper (II) oxide.

(b) (1) State two uses of ammonia.

(ii) Name the catalyst used in the preparation of ammonia.

(c) Explain each of the following reactions, giving observations and equations.

3. Aqueous ammonia is added to iron (III) chloride, little by little, until in excess.

4. Sodium nitrate is strongly heated.