Calculate [ClO^-] in a 6% bleach solution. A 6% bleach solution contains 6 grams of NaClO per 100 grams bleach. The density of 6% bleach is 1.07g/mL.

Answer 1

Percent w/w is a perfectly good concentration to use. What do you want it in? molarity.
6g/100 g soln.
mols in 6g = 6/molar mass NaClO.
100 g soln converted to L is ?
volume = mass/density 100/1.07 = ?

So M = mols/L soln. Substitute mols and L and you have it. (That's the molarity of NaClO but it also is M ClO^-

Answer 2

Then calculate the inital ClO^- concencentrations for 1st, 2nd, and 3rd reactions.

Chemical reaction: Blue dye + ClO^- -->oxidized dye +Cl^-

Reaction #1: 5.0 mL or diluted bleach solution, 15.0mL of distilled water, 10.0 mL of diluted blue dye
Reaction #2: 10.0mL of diluted bleach solution, 10.0mL distilled water, 10.0mL diluted blue dye
Reaction #3:20.0 mL diluted bleach, 10.0 mL of diluted blue dye, 0mL of distilled water