Chemistry
Give one test each to distinguish between the following pairs of chemical solutions
(i) Zn(NO3)2 and Ca(NO3)2
(ii) NaNO3 and NaCl
(iii) Iron [III] chloride and copper chloride .
Answer
(i) 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.
(ii) Add conc. sulphuric acid to the given salts, NaCl will react to produce HCl gas, which produces dense white fumes when a glass rod dipped in ammonia soln. is brought near it. If we add copper turnings along with conc. sulphuric acid, NaNO3 will react to give reddish brown nitrogen dioxide. Hence, the two salts can be distinguished.
(iii) When we add NaOH solution to the given solutions, Iron [III] chloride forms a reddish brown ppt. of Fe(OH)3 whereas, copper chloride gives a pale blue ppt of Cu(OH)2.
Related Questions
From the list of substances given — Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State : A substance that turns moist starch iodide paper blue.
State what is observed when excess of ammonia passed through an aqueous solution of lead nitrate.
Give a reason why carbon dioxide and sulphur dioxide cannot be distinguished by using lime water.
Salts A, B, C, D and E undergo reactions (i) to (v) respectively. Identify the anion present in each salt.
(i) When AgNO3 solution is added to a soln. of A, a white precipitate, insoluble in dilute nitric acid, is formed.
(ii) Addition of dil. HCl to B produces a gas which turns lead acetate paper black.
(iii) When a freshly prepared solution of FeSO4 is added to a soln. of C and conc. H2SO4 is gently poured from the side of the test-tube, a brown ring is formed.
(iv) When dil. H2SO4 is added to D a gas is produced which turns acidified K2Cr2O7 soln. from orange to green.
(v) Addition of dil. HCl to E produced an effervescence. The gas produced turns limewater milky but does not effect acidified K2Cr2O7 soln.