Sodium hypochlorite,NaOCl,is the active ingredient in household bleach.What is the concentration of hypochlorite ion if 20.00 mL of bleach requires 32.00 mL of 0.500 M HCl to reach the equivalence point?
A)0)300 M
B)0)312 M
C)0)800 M
D)1)30 M

Question

Quizplus · Accepted Answer

The balanced chemical equation for the reaction between NaOCl and HCl is:

NaOCl + HCl → NaCl + H2O + Cl2

From the equation, we can see that 1 mole of NaOCl will react with 1 mole of HCl to produce 1 mole of Cl2. Therefore, the number of moles of Cl2 produced in the reaction is equal to the number of moles of hypochlorite ion (OCl-) in the bleach.

First, we need to calculate the number of moles of HCl used:

n(HCl) = C(HCl) x V(HCl) = 0.500 M x 0.03200 L = 0.016 mol

Since the reaction is a 1:1 stoichiometry between HCl and NaOCl, the number of moles of NaOCl used is also 0.016 mol. Therefore, the concentration of hypochlorite ion in the bleach can be calculated as follows:

[OCl-] = n(OCl-) / V(bleach) = 0.016 mol / 0.02000 L = 0.800 M

So, the answer is C) 0.800 M.

Sodium Hypochlorite,NaOCl,is the Active Ingredient in Household Bleach