All your burette readings (initials and final), as well as the size of your pipette, must be recorded but no account of experimental procedure is required. All calculations must be done in your answer booklet. (a) State what would be observed when BaCl, the solution is a portion of a saturated Na\(_2\)CO\(_2\) followed by dilute HCI in excess. (ii) A gas Q decolorized acidified kM\(_n\)O\(_4\) Solution. Suggest what Q could be
(b) Name one substance used in the laboratory for drying each of the following substances: (i) ammonia gas: (ii) carbon (IV) oxide.
(c) Give a reason why a given mass of sodium hydroxide pellets cannot be used to prepare a standard solution.
Explanation
(a) BaCl\(_{2(aq)}\) + Na\(_2\)CO\(_{3(aq)}\) followed saturated by dilute HCl in excess - A white precipitate is formed. - Effervescence occurs and a gas evolved and the white precipitate dissolves in excess dil HCl (ii) Gas Q that decolourized acidified KMnO\(_2\) solution could be any of these. SO\(_{2(g)}\), H\(_2\)S\(_{(g)}\), unsaturated hydrocarbon (C\(_2\)H\(_{2}\), C\(_2\)H\(_4\)....)
(b) One substance used in the laboratory for drying each of the following: (I) ammonia gas - Calcium oxide (ii) carbon (IV) Oxide - Calcium chloride - Concentrated tetraoxosulphate( VI) acid.
(c) Sodium hydroxide pellets cannot be used to prepare a standard solution because it is deliquescent, it absorbs water vapour (moisture) and carbon (IV) oxide from the air, and this would add to its mass.
