MediumChemistryHigh School (11–12)Principles Related to Practical ChemistryNumericalAEEE (Amrita)AMUEEEAP EAPCETBCECECOMEDK UGETGUJCET
A teaching laboratory holds ten sodium salts: carbonate, sulphide, sulphite, nitrite, acetate…
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A teaching laboratory holds ten sodium salts: carbonate, sulphide, sulphite, nitrite, acetate, chloride, bromide, iodide, nitrate and sulphate. Five observations are made with each. The first is whether the salt gives a gas or vapour with dilute sulphuric acid. The second is whether barium chloride solution gives a white precipitate. The third is whether any of those precipitates stays in dilute hydrochloric acid. The fourth is whether the salt gives a coloured vapour with concentrated sulphuric acid and no other reagent. The fifth is whether the salt gives no result for the first, second or fourth observation. Count the salts for each one.
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Dilute acid. Carbonate, sulphide, sulphite, nitrite and acetate: 5.
Step 2. Barium chloride. Carbonate, sulphite and sulphate give white precipitates: 3.
Step 3. Stays in dilute acid. The carbonate and the sulphite dissolve. Only barium sulphate stays: 1.
Step 4. Coloured vapour. Bromide gives reddish brown vapour and iodide gives violet vapour: 2.
Step 5. No result. The salts that appear in none of the three sets are chloride and nitrate: 2.
Answer: 5, 3, 1, 2 and 2.
Check. The sets for the first, second and fourth observations hold salts with carbonate and sulphite counted twice, so they cover 8 different salts. .
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