I\'ve asked this question and the Chegg expert gave me the answer 70.9, which is
ID: 958341 • Letter: I
Question
I've asked this question and the Chegg expert gave me the answer 70.9, which is wrong. Please help. Thanks
A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH 10.23 solution. Number 70.9 mL Tools ×102 ' O Previous ) Give Up & View Solution e Check Answer Next Hint Hypochlorite ion, Oci, is sometimes written as CIO. Its conjugate acid, hypochlorous acid, can be written either as HOCI or HCIO Use the Ka of hypochlorous acid to determine the Kb of hypochlorite.Explanation / Answer
denisty = 1 g/mL
mass % = 5.25 %
formula for molarity = wt% x 10 x d / molar mass
moalrity of NaOCl initial = wt % x 10 x d / molar mass
= 5.25 x 10 x 1 / 74.44
= 0.705 M
V1 = ?
pH = 10.23
pH + pOH = 14
pOH = 3.77
[OH-] = 10^-3.77 = 1.70 x 10^-4 M = x
OCl- + H2O ------------------> HOCl + OH-
C2 0 0 -------------> initial
C2-x x x -------------> equilibrium
Kb = x^2 / C2-x
2.08 x 10^-7 = (1.70 x 10^-4)^2 / C2 - 1.70 x 10^-4
C2 - 1.70 x 10^-4 = 0.1389
C2 = 0.139 M
V2 = 500 mL
C1 V1 = C2 V2
0.705 x V1 = 0.139 x 500
V1 = 98.66 mL
answer : volume = 98.66 mL