(a) Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode.
(a) Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode.
Solution
(a)
• When electricity is passed through brine, it decomposes to form
sodium hydroxide (alkali) and chlorine, hence this process is
called chlor-alkali process.
Electricity
2NaCl(aq) + 2H2 O(l) → 2NaOH(aq) + H2 (g) + Cl2 (g)
• At anode: Cl2
• At cathode: H2
OR
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(b)
(i) NaCl + H2 O + NH3 + CO2 → NaHCO3 + NH4 Cl
(ii) Ca(OH)2 + Cl2 → CaOCl2 + 𝐻2 𝑂
/
2Ca(OH)2 + 2Cl2 → Ca(ClO)2 + CaCl2 + 2H2O
373K
(iii) CaSO4 .2H2 O →
CaSO4 . 2 H2 O + 1 2 H2 O
(deduct ½ mark for no / incorrect balancing)