- In the manufacture of sodium hydroxide, hydrogen gas and chlorine gas (X) are formed as by–products.
- When chlorine gas (X) reacts with lime water, it forms calcium oxychloride (bleaching powder) Y.
- The reactions are :
2NaCl (aq) + 2H2O(l) → 2NaOH (aq) + Cl2(g) + H2(g)
X→ Cl2 (Chlorine gas)
Ca (OH)2 (s) + Cl2 (g) → CaOCl2 (s) + H2O
Y — Calcium oxychloride (bleaching powder)