(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...
Question 1 Report
(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.
Answer Details
(a)(i) Two uses of chlorine are:
- sterilising drinking water and swimming-pool water;
- manufacture of bleaching agents and for bleaching wood pulp and textiles.
(a)(ii) Chlorine first turns moist blue litmus paper red and then bleaches it white.
(b) A dry sample of chlorine is prepared by warming manganese(IV) oxide with concentrated hydrochloric acid. The gas is washed with saturated sodium chloride solution to remove hydrogen chloride, dried with concentrated tetraoxosulphate(VI) acid, and collected by downward displacement of air.
\[\mathrm{MnO_2(s)+4HCl(aq)\rightarrow MnCl_2(aq)+2H_2O(l)+Cl_2(g)}\]
(c)(i) Chlorine reacts with aqueous iron(II) chloride by a redox reaction. Iron(II) ions are oxidised to iron(III) ions.
\[\mathrm{Cl_2(aq)+2Fe^{2+}(aq)\rightarrow 2Cl^-(aq)+2Fe^{3+}(aq)}\]
Equivalently:
\[\mathrm{Cl_2(aq)+2FeCl_2(aq)\rightarrow 2FeCl_3(aq)}\]
(c)(ii) Chlorine reacts with propane in sunlight or ultraviolet light by a substitution reaction (free-radical substitution).
\[\mathrm{C_3H_8(g)+Cl_2(g)\xrightarrow{UV\ light}C_3H_7Cl(g)+HCl(g)}\]
The organic product is chloropropane, formed as a mixture of 1-chloropropane and 2-chloropropane.
(d) The increasing order of oxidising ability is:
\[\mathrm{Br_2 < Cl_2 < F_2}\]
Chlorine oxidises bromide ions to bromine, so chlorine is a stronger oxidising agent than bromine. Fluorine oxidises chloride ions to chlorine, so fluorine is a stronger oxidising agent than chlorine.
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