Chemistry Question Help!!!

Someone please please help me with this question! It would be most appreciated!!

A student does an experiment to determine the percentage by mass of sodium chlorate(1), NaCIO, in a sample of bleach solution.
Method: . Dilute a 10.0 cm sample of bleach solution to 100 cm with distilled water. Transfer 25.0 cm3 of the diluted bleach solution to a conical flask and acidify using sulfuric acid. . Add excess potassium iodide to the conical flask to form a brown solution containing Iz(aq) . Add 0. 100 mol dm- sodium thiosulfate solution (NazS203) to the conical flask from a burette until the brown solution containing Iz(aq) becomes a colourless solution containing I-(aq).

The student uses 33.50 cm of sodium thiosulfate solution. The density of the original bleach solution is 1.20 g cm-3.

The equations for the reactions in this experiment are
CIO-(aq) + 2H+(aq) + 2I-(aq) -> Cl-(aq) + H20(l) + I2(aq)
2S2032-(aq) + I2(aq) -> 2I-(aq) + S4062-(aq)

Use all the information given to calculate the percentage by mass of NaCIO in the original bleach solution.

Reply 1

replaythat

4.16%

(33.50/1000)*0.100 = 3.35*10^-3 = mols of S2O3-
(3.35*10^3)/2 = 1.675*10^-3 = mols of ClO-
1.6745*10^-3 *4 = 6.7*10^-3 = dilute it back up (100/25 = 4)
6.7*10^-3 * (23+35.5+16) = 0.49915g (mass = mols*mr)
1.20*10 = 12.0 (mass of the original solution - density*volume = mass)
(0.49915/12)*100= 4.159583

Reply 2