Chemistry
Give a chemical test in each case to distinguish between the following pairs of chemicals.
(i) Sodium chloride solution and sodium nitrate solution.
(ii) Sodium sulphate solution and sodium chloride solution.
(iii) Calcium nitrate solution and zinc nitrate solution.
Analytical Chemistry
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Answer
(i) Add silver nitrate soln. to the given solns., sodium chloride reacts to form a white ppt. which is soluble in NH4OH and insoluble in dil. HNO3. The other soln. is sodium nitrate.
NaCl + AgNO3 ⟶ AgCl + NaNO3
NaNO3 + AgNO3 ⟶ no white ppt.
(ii) Sodium sulphate solution reacts with barium chloride to form white ppt. of barium sulphate and sodium chloride, whereas, no reaction takes place in case of sodium chloride solution because both of them have the same anion.
Na2SO4 + BaCl2 ⟶ BaSO4 ↓ [white ppt.] + 2NaCl
NaCl + BaCl2 ⟶ no reaction
(iii) When NaOH is added to the given soln., Zn(NO3)2 reacts to form a gelatinous white ppt. which dissolves in excess of NaOH whereas, Ca(NO3)2 forms a milky white ppt. which is insoluble in excess of NaOH. Hence, the two can be distinguished.
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