Busisiwe asked in Science & MathematicsChemistry · 6 months ago

# a 100 mL of a2.00 M NaCl was electrolyzed for 25 min with 1.45 A what is the concentration of hypochlorite produced?

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• 6 months ago

Chlorination of water by electrolysis

The electrolysis of brine produces H2 gas and Cl2 gas in a basic solution. Cl2 gas reacts with water to produce HOCl(aq) and HCl(aq). But in basic solution the products are OCl- and Cl- (which is one of the reactants). Without going through all the steps, the overall reaction is:

.... NaCl(aq) + H2O(l) --electricity --> NaOCl(aq) + H2(g)

.............. Cl- + H2O(l) --electricity --> OCl- + H2(g)

..............100 mL ............ ....................?M

Cl- + 2OH- --> OCl- + H2O + 2e- .......... oxidation half-reaction

2 mol e- per mol of Cl- and OCl-

25 min x (60s / 1 min) x (1.45 C / 1s) x (1 mol e- / 96485C) x (1 mol OCl- / 2 mol e-) / 0.100L = 0.113M OCl- ................. 0.0113 mol OCl- is produced

========= =========

Reduction half-reaction

2H2O + 2e- --> H2 + 2OH-

25 min x (60s / 1 min) x (1.45 C / 1s) x (1 mol e- / 96485C) x (1 mol H2O / 1 mol e-) = 0.0225 mol H2O ............ 0.0225 mol H2O is reduced, 0.0113 mol H2 is produced

2H2O + 2e- --> H2 + 2OH- ................... reduction half-reaction

Cl- + 2OH- --> OCl- + H2O + 2e- .......... oxidation half-reaction

----------------- ----------------- -------------

Cl- + 2OH- + 2H2O --> OCl- + H2O + H2 + 2OH-

simplify

Cl- + H2O --> OCl- + H2

Cl- .......+...... H2O -------> OCl- ...+... H2

0.0113 mol .. 0.0113 mol ....0...............0 .................. before reaction

.0........... .......0............ 0.0113 mol .. 0.0113 mol...... after reaction