Add dilute hydrochloric acid to a small portion of each unknown solution.
This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
ScanSolve AI Answer
c) To identify the two solutions:
Step 1: Add dilute hydrochloric acid to a small portion of each unknown solution.
• The solution containing sulphite ions will produce a colorless gas with a pungent smell ($\text{SO}_2$), which turns acidified potassium dichromate(VI) solution from orange to green.
$$ \text{SO}_3^{2-}(aq) + 2\text{H}^+(aq) \to \text{SO}_2(g) + \text{H}_2\text{O}(l) $$
• The solution containing sulphate ions will show no visible reaction.
Step 2: To the solution that showed no reaction with dilute hydrochloric acid (from Step 1), add a few drops of barium chloride solution.
• A white precipitate will form, which is insoluble in dilute hydrochloric acid. This confirms the presence of sulphate ions.
$$ \text{Ba}^{2+}(aq) + \text{SO}_4^{2-}(aq) \to \text{BaSO}_4(s) $$
4. a) Isomers are compounds that have the same molecular formula but different structural formulas or different arrangements of atoms in space.
4. b) The molecular formula $\text{C}_4\text{H}_{10}$ has two isomers:
• Butane
$$ \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3 $$
• 2-Methylpropane
$$ \text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_3 $$
4. c)
i) • Chlorination of ethane: Free radical substitution
• Chlorination of ethene: Electrophilic addition
ii) A condition necessary for chlorination of ethane is ultraviolet (UV) light or high temperature.
4. d) Two uses of ethene gas are:
• For the ripening of fruits.
• In the manufacture of polyethene (a plastic).
4. e) Heat of combustion of a substance is the heat energy released when one mole of a substance undergoes complete combustion in excess oxygen under standard conditions.
Send me the next one 📸
