Variations in Obtaining gL-1

[vexx]

Hi.

I was doing Q34 in the heinemenn which its last question is
"What is the concentration of sodium hypochlorite(NaOCl) in g L–1?"

Previously i had just gotten the mol of NaOCl at 0.01276mol (in 20ml), and then the amount in grams (mol x ~75 = 0.9502g)

And to get the amount in gram per litre, i found the concentation of NaOCl (0.01276/0.020=0.638 M) and then timed the concentration by the molar mass ~75 to get 47.53gL-1.

However, the answers say to use the amount in grams 0.9502g and do (x1000/25) to get 38.02gL-1.

Isn't the way i did it also correct, i've only been doing it my way usually and it's worked, why is this new way different and when will i be expected to do it this way?

Thanks,

Vexx.

[physics]

In my Heinemann it said tojust multiply the conecntration by the molar mass of the substance.,... (i think u said that already)

...the other way seems jibby...i wouldn't trust it XD

[Potter]

I think they made a mistake, it should be mass x 1000/20. Using 25 doesn't make sense at all..

[vexx]

I think they made a mistake, it should be mass x 1000/20. Using 25 doesn't make sense at all..

Ah okay, that would make sense then.
I'll just ignore the question

Thanks peoples:)

[simonhu81292]

I think they made a mistake, it should be mass x 1000/20. Using 25 doesn't make sense at all..

Ah okay, that would make sense then.
I'll just ignore the question

Thanks peoples:)

hey vexx...just wanted to say that ... using either way still works..
as potter stated..it is the 25ml and the 20ml error...
if you play with the formulas... your concentration times molar mass will give you your grams per litre
 :smitten:

[vexx]

I think they made a mistake, it should be mass x 1000/20. Using 25 doesn't make sense at all..

Ah okay, that would make sense then.
I'll just ignore the question

Thanks peoples:)

hey vexx...just wanted to say that ... using either way still works..
as potter stated..it is the 25ml and the 20ml error...
if you play with the formulas... your concentration times molar mass will give you your grams per litre
 :smitten:

yeah i tried both and it worked:) thanks.