Question

1. Action of heat on the following compounds: a. CuCO3, ZnCO3 b. Zn(NO3)2, Cu(NO3)2, Pb(NO3)2 Make observations, identify the products and make deductions where possible. 2. Identification of ions by preparing solution and by adding of NaOH and NH4OH. Ca2+, Cu2+, Fe2+, Fe3+, Pb2+, Zn2+, NH4 1+ 3. Supply a solution of a dilute acid and alkali. Determine which is acidic and which is basic. Give two tests for each. 4. Add concentrated hydrochloric acid to each of the given substances, warm, make observations, Identify any product and make deductions: a. Copper oxide. b. Manganese dioxide.​

Answer 1

Answer:

CuCO3, ZnCO3 b. Zn(NO3)2, Cu(NO3)2, Pb(NO3)2

Answer 2

Answer:

1. Action of heat:

a) $CuCO_{3}$ decomposes into copper oxide CuO and carbon dioxide $CO_{2}$.

$ZnCO_{3}$ decomposes into zinc oxide ZnO and carbon dioxide  $CO_{2}$.

b. $Zn(NO_{3})_{2}$ undergoes thermal decomposition and breaks down into zinc oxide ZnO, nitrogen dioxide $NO_{2}$ and oxygen $O_{2}$.

$Cu(NO_{3})_{2}$ undergoes thermal decomposition and breaks down into zinc oxide CuO, nitrogen dioxide  $NO_{2}$ and oxygen $O_{2}$.

$Pb(NO_{3})_{2}$ undergoes thermal decomposition and breaks down into lead oxide PbO, nitrogen dioxide  $NO_{2}$ and oxygen $O_{2}$.

2. Identification of cations:

$Ca^{+2}$ gives white precipitate of $Ca(OH)_{2}$ when reacted with NaOH.

$Cu^{+2}$ gives pale blue precipitate of $Cu(OH)_{2}$ when reacted with NaOH.

$Fe^{+2}$ gives green precipitate of $Fe(OH)_{2}$ when reacted with NaOH.

$Fe^{+3}$ gives reddish brown precipitate of $Fe(OH)_{3}$ when reacted with NaOH.

$Pb^{+2}$ gives gelatinous white precipitate of $Pb(OH)_{2}$ when reacted with $NH_{4}OH$.

$Zn^{+2}$ gives white precipitate of $Zn(OH)_{2}$ when reacted with NaOH.

$NH_{4}^{+1}$ liberates ammonia gas when reacted with NaOH.

3. Tests for acid and alkali

Litmus test: Red litmus turns blue in alkaline solution, and blue litmus turns red in acidic solution.

pH paper/pH meter: Using a pH paper or a pH meter, one can accurately find out the pH of a given solution.

4. Reaction with conc. HCl

Copper oxide when reacted with conc. HCl gives copper chloride $CuCl_2$and water $H_2O$ as a product.

Manganese dioxide when reacted with conc. HCl gives chlorine gas $Cl_2$, manganese chloride $MnCl_2$ and water $H_2O$  as products.

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