when NaOH added
NaOH + HOCl --------------> NaOCl + H2O
moles of HOCl = 0.05
moles of NaOCl = 0.04
moles of NaOH added = 1.0 x 0.01 =0.01
final moles of HOCl = 0.05 - 0.01 = 0.04
final moles of NaOCl = 0.01 + 0.01 = 0.05
total volume = 100 + 10 = 110 mL = 0.11 L
Molarity of NaOCl = 0.05 / 0.11 = 0.45 M
molarity of HOCl = 0.04 / 0.11 = 0.36 M
pH = pKa + log [NaOCl] / [HOCl]
pKa = -log Ka = -log [3.5 x 10-8] = 7.45
pH = 7.75 + log [0.45] / [0.36]
pH = 7.85
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