(a)(i) Give two uses of chlorine.
(ii) State the action of chlorine on moist blue litmus paper
(b) Draw a labelled diagram for the laboratory preparation of a dry sample of chlorine
(c) State the type of reaction involved between chlorine and (i) aqueous iron (II) chloride;
(ii) propane. Write an equation for each reaction and name the product formed in (c)(ii).
(d) Consider the reactions the following equations: Cl\(_{2(g)}\) + 2Br\(^-_{(aq)}\) \(\to\) 2Cl\(^-_{(aq)}\) + Br\(_{2(g)}\)
F\(_{2(g)}\) + 2Cl\(^-_{(aq)}\) ---> 2F\(^-_{(aq)}\) + Cl\(_{2(g)}\)
From the equations, arrange bromine, chlorine and fluorine in increasing order of oxidizing ability. Give the reason for your answer.
(a) Name one gaseous hydrocarbon which is
(i) used for welding.
(ii) a major raw material for the plastic industry.
(b) Write the structural formula of the hydrocarbon in (a)(i) above. Name the process by which it can be converted to neoprene rubber.
(c) Potatoes contain a high proportion of carbohydrate.
(i) Give the main product formed when potatoes are dehydrated completely
(ii) Describe how you would convert potatoes to ethanol. State the reactions involved the process and write equation for the final stage of the conversion.
(iii) Draw a labelled diagram of the apparatus you would use to obtain a sample of fairly pure ethanol from the product formed in (c)(ii) above. What is the name given to the technique?
(a) Give three differences between electrovalent compounds and covalent compounds
(b) List two physical properties of metals which can be accounted for by their structure
(c) Thorium (Th) metal undergoes a reaction represented by the following equation:
\(^{234}_{90}Th \to X + ^{234}_{91}Pa\)
(i) State the type of process involved in the reaction
(ii) Balance the equation equation and hence identify X.
(iii) Name one equipment which can be used to detect X.
(iv) Sketch a curveto show the mass of given quantity of thorium will change over a long period of time.
(d) Y is a moderately reactive divalent found naturally in the combined state as the trioxocarbonate (IV) salt, YCO\(_3\) is decomposed by strong heat, state the steps you would use in extracting Y from the ore. Write equation to show the chemical processes involved.
(a) State two factors which can affect the rate of a chemical reaction.
(b) 0.72g of magnesium was added to different volumes of 2 mol. per dm\(^3\) hydrochloric acid. The volume of liberated was as measured at room temperature and pressure. The result of the experiment was as tabulated
| vol. of 2 mol. per dm\(^3\) HCl used (cm\(^3\) | Vol. of H\(_2\) evolved in cm\(^3\) (to the nearest 10cm\(^3\)) |
|
5 15 25 35 45 |
120 360 550 600 600 |
Use the data in the table to plot a graph of the volume of hydrogen liberated against the volume of acid used.
(c) From the graph in (b) above, determine the volume of: (i) hydrogen that would be produced if 50 cm\(^3\) of the acid were added to 0.72g of magnesium.
(ii) the acid which must be added to 0.72 g of magnesium to produce 480 cm\(^3\) of hydrogen;
(iii) the acid needed exactly to dissolve 0.72 g of magnesium completely.
(d) Explain your answer to (c)(iii).
(e) From your answers to (c) above, deduce the: (i) volume of the acid which will dissolve 1 mole of magnesium completely. (Mg = 24)
(ii) volume of hydrogen that would be liberated if 1 mole of magnesium dissolves completely in the acid;
(iii) equation for the reaction between magnesium and hydrochloric acid. Show clearly how you arrived at you answers
(a) Name the apparatus used in the laboratory to (i) Convert vapour into liquid during distillation
(ii) determine the volumetric composition of water
(ii) produce an intermittent supply of any gas which can be evolved by the action of a liquid on a solid without heating.
(b) Give the reason for the following;
(i) the edge of the lid of a desiccator should be greased
(ii) a standard solution of sodium hydroxide is not prepared by weighing out accurately a given mass of the solid and making it up to the required volume.
iii) after the reduction of copper (II) oxide by a a stream of hydrogen gas passed overs the heated oxide in a combustion tube, it is necessary to continue passing the gas over the residue until the residue cools.
(c) An acid-base indicator turns orange in an acidic solution, green in a neutral solution and blue in an alkaline solution. The table shows the results obtained when a few drops of the indicator were added to samples of some liquids.
| Liquid | Colour of the indicator in the liquid |
|
Glucose solution Rainwater Lime water Vinegar Stomach powder solution |
Green Pale orange Blue Orange Pale blue |
(i) Arrange the liquids in increasing order of their expected pH values.
(ii) Explain why the colour of the indicator in the sample of rainwater is pale orange whereas in pure water it is green.
(iii) A given crystalline solid is suspected to be either sodium chloride or ammonium tetraoxosulphate (VI). Describe how you would use the indicator to identify the solid.
(iv) State with reason whether or not phenolphthalein indicator can be used to distinguish between the samples of glucose solution and vinegar.
(v) What would be the colour of methyl orange indicator in the lime water sample?
