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Bleach concentration, please help

Hi,
I found the following info online when I was trying to get something to help with my work, I'm confused by it so I'll type it out as best as I can and then explain what confuses me:

25 ml of 1:10 diluted Clorex was titrated against sodium thiosulphate. Avg. thiosulphate used = 32.7 cm ^3

In this reaction, 2 moles of thiosulphate are used up by 1 mole of the hypochlorite in the bleach

Molar mass sodium hypochlorite in bleach= 74.5

I understand everything above

No. of Mole/volume = M

The no. of mole of diluted NaClO
1/2 x 0.1 x 32.7/1000 = 1.635 x 10 ^-3

Ok, here, they have multiplied the concentration of the thiosulphate (0.1) by a half as the ratio is 2:1 (above) and the volume is converted into litres, so I am OK with this

The no. of mole of NaClO = 1.635 x 10 ^-3 x 10
= 1.635 x 10 ^-2

There was no explanation against this step, but I believe that the value is multiplied by 10 as the bleach was a 1 in 10 dilution

mole x molar mass / volume = g/cm^3

1.635 x 10^-2 x 74.5 / 25 = 0.0487 g/cm^3

No explanation was given for this last step which is where the majority of my confusion lies. Where did the calculation come from? I don't recognise it and can't make sense of it. And why was the volume used as 25? Why was it not converted into litres? Can anyone make sense of it?

In my report, I need to present the hypochlorite content as a percentage, how would I do this?
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EquusSomnium
OP
8
Ok... I just found this online:
Moles thiosulfate used = (molarity of thiosulfate)x(volume thiosulfate used)

Mass NaOCl titrated = (moles hypochlorite titrated)x(molar mass NaOCl)
How do I work out the moles of hypochlorite titrated?

Volume of commercial bleach titrated = (volume dilute bleach titrated)x(dilution ratio (10/100))

I used 25 ml of diluted bleach, and it was diluted 1:10, so, do I multiply 25 by 0.1? or do I use the volume in litres?

Mass of commercial bleach titrated = (density of commercial bleach)x(volume of commercial bleach titrated)
How do I calculate the density of the bleach?

% NaOCl in commercial bleach = (mass NaOCl titrated/mass commercial bleach titrated) x 100%

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