(a)(i) Draw a labelled diagram for the laboratory preparation of a dry sample of chlorine (ii) Give one chemical test for chlorine. (b) Write equations to r...

(a)(i) Laboratory preparation of a dry sample of chlorine

Heat manganese(IV) oxide with concentrated hydrochloric acid. The chlorine produced is passed through saturated brine (or aqueous potassium hydrogencarbonate) to remove hydrogen chloride, then through concentrated sulphuric acid to dry it. It is collected in an upright gas jar by downward displacement of air, since chlorine is denser than air.

\[\mathrm{MnO_2(s)+4HCl(conc)\rightarrow MnCl_2(aq)+Cl_2(g)+2H_2O(l)}\]

(ii) Test for chlorine

Hold moist starch-iodide paper in the gas. It turns blue-black because chlorine liberates iodine from iodide ions.

\[\mathrm{Cl_2+2I^-\rightarrow 2Cl^-+I_2}\]

(b) Equations for the reactions of chlorine

(i) With iron(II) chloride solution:

\[\mathrm{Cl_2+2FeCl_2\rightarrow 2FeCl_3}\]

(ii) With potassium iodide solution:

\[\mathrm{Cl_2+2KI\rightarrow 2KCl+I_2}\]

(iii) With hot concentrated sodium hydroxide solution:

\[\mathrm{3Cl_2+6NaOH\rightarrow 5NaCl+NaClO_3+3H_2O}\]

(c)

(i) A white precipitate of lead(II) chloride is formed when hydrogen chloride gas is bubbled into lead(II) trioxonitrate(V) solution.

\[\mathrm{Pb(NO_3)_2(aq)+2HCl(aq)\rightarrow PbCl_2(s)+2HNO_3(aq)}\]

(ii) The white precipitate dissolves on heating to boiling. On cooling, white crystals of lead(II) chloride reappear.

(d)

A white precipitate or milky suspension of bismuth oxychloride, \(\mathrm{BiOCl}\), forms when water is added.

Adding water dilutes the hydrochloric acid and shifts the equilibrium to the left. Soluble \(\mathrm{BiCl_3}\) is thereby converted into insoluble white \(\mathrm{BiOCl}\):

\[\mathrm{BiOCl(s)+2HCl(aq)\rightleftharpoons BiCl_3(aq)+H_2O(l)}\]