Question

(i) What happens when (write chemical equation only):
\begin{enumerate} \item Plaster of Paris reacts with water? \item \(\text{NH}_3 (g)\) and \(\text{CO}_2 (g)\) are passed in the solution of saturated aqueous solution of NaCl? \item \(\text{Ca(OH)}_2\) (dry) reacts with \(\text{Cl}_2\) (g) (dry)? \end{enumerate}

Hint:

1. Plaster of Paris forms gypsum when mixed with water. 2. NH₃ and CO₂ react with NaCl to form ammonium chloride and sodium bicarbonate. 3. Calcium hydroxide reacts with chlorine gas to form calcium chloride and calcium oxychloride.

Answer 1

1. Plaster of Paris reacts with water:
When Plaster of Paris (\(CaSO_4. \frac{1}{2} H_2O\)) reacts with water, it forms gypsum (\(CaSO_4. 2H_2O\)): \[ \text{CaSO}_4. \frac{1}{2} \text{H}_2\text{O} + \text{H}_2\text{O} \rightarrow \text{CaSO}_4. 2\text{H}_2\text{O} \] 2. NH_3 (g) \text{ and CO}_2 (g) \text{ is passed in the solution of saturated aqueous solution of NaCl:}
When ammonia (\(NH_3\)) and carbon dioxide (\(CO_2\)) gases are passed through a saturated aqueous solution of sodium chloride (\(NaCl\)), they form ammonium chloride (\(NH_4Cl\)) and sodium bicarbonate (\(NaHCO_3\)): \[ \text{NH}_3 (g) + \text{CO}_2 (g) + \text{NaCl} (aq) \rightarrow \text{NH}_4\text{Cl} (aq) + \text{NaHCO}_3 (aq) \] 3. Ca(OH)_2 (dry) \text{ reacts with Cl}_2 (dry):}
When dry calcium hydroxide (\(Ca(OH)_2\)) reacts with chlorine gas (\(Cl_2\)), it forms calcium chloride (\(CaCl_2\)) and calcium oxychloride (\(Ca(OCl)_2\)): \[ \text{Ca(OH)}_2 + \text{Cl}_2 \rightarrow \text{CaCl}_2 + \text{Ca(OCl)}_2 + \text{H}_2\text{O} \]