acid/base

[vhebi]

Sodium hypochlorite, NaOCl, is the active ingredient in household bleach. What is the concentration of hypochlorite ion if 20.00 cm3 of bleach requires 25.30 cm3 of 0.500 M HCl to reach the equivalence point?




a. 1.13 M b. 0.132 M c. 0.395 M d. 0.632 M

[sharan]

at equivalance point,

C₁V₁= C₂V₂

Therefore,
C₁V₁ (Hypochlorite) = C₂V₂ (HCl)
20 cm3 * C₁ = 25.30 cm3 * .5 M
C₁= ( 25.3 * .5 )/ 20
=.6325 or ~0.633 [with 3 significant digits after point (.)]

hope that helps...

-Sharan