(a) Name the gas evolved when dilute hydrochloric acid is added to each of the following solids and the mixture is warmed (i) sodium trioxocarbonate (IV); (...
Question 1 Report
(a) Name the gas evolved when dilute hydrochloric acid is added to each of the following solids and the mixture is warmed
(i) sodium trioxocarbonate (IV);
(ii) potassium trioxosulphate (IV);
(iii) iron (II) sulphide.
(b) Name the reagent(s) that you would use to identify the gas in (a)(ii) above.
Answer Details
(a) Gas evolved on warming each solid with dilute hydrochloric acid:
- (i) Sodium trioxocarbonate(IV), Na\(_2\)CO\(_3\): carbon dioxide, CO\(_2\). \[Na_2CO_3 + 2HCl \to 2NaCl + H_2O + CO_2\uparrow\]
- (ii) Potassium trioxosulphate(IV), K\(_2\)SO\(_3\): sulphur(IV) oxide (sulphur dioxide), SO\(_2\). \[K_2SO_3 + 2HCl \to 2KCl + H_2O + SO_2\uparrow\]
- (iii) Iron(II) sulphide, FeS: hydrogen sulphide, H\(_2\)S. \[FeS + 2HCl \to FeCl_2 + H_2S\uparrow\]
(b) Reagent to identify the gas in (a)(ii), SO\(_2\): acidified potassium tetraoxomanganate(VII) solution, which is decolourised (purple to colourless) by the sulphur dioxide; alternatively acidified potassium dichromate(VI), which turns from orange to green.
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