Zinc sulphate

[cheltie]

Hi everyone,
Can someone work out for me what molarity a 5% solution of zinc sulfate is please?
I am not sure how you convert from one to the other.
Thanks,
Helen

[dime]

Just wondering why you would need to convert. Unfortunately I don't know, but if I'm asked for a 5% solution I just give it to them and mark it as such. It would be approx 0.2M for purposes of knowing how to colour code it. Hope this helps.

[cheltie]

Hi Dime,
I have a 5% solution made up. The teacher wants a .1M solution and I have run out of solid.
I told her it was about 1.6 just working it out in my head but she wanted an exact figure and I am not sure how to do this.
Helen

[Jen Jen]

Percentage sol. 1g solid per. 100ml. of water

[MariaC]

You need 28.8g made up to a litre to make 0.1M, therefore 2.88g to make 0.1M/100mls you have approx twice this so roughly 0.2M or 0.174M to be exact (5g devided by 2.88g) I think thats right! MariaC

[Krysia Lee]

Hi Helen
Don't know if this will help but I have this formula for percent to molar solutions

required molarity x molecular weight x volume required (in mL)
mL of stock solution required = ________________________________________________________
stock percentage x 10

Once you have the amount of stock required you make up to 1L. Hope that helps
Krysia

[Krysia Lee]

Hi Again
that post didn't come out quite like it should. What it is in long hand is that the amount of stock solution required ( here your 5% solution)is equal to the required molarity x molecular weight x volume required divided by the stock percantage x 10. Or for a 0.1M you need 0.1 x 287.54 x1000 =28754 divided by 50 =575.08mL Then make up to 1L.
Krysia

[cheltie]

Thanks,
I knew someone would be smart enough to work it out for me!!
Helen

[Krysia Lee]

HI
There is a good website that has a calculator for working out lots of different solution probs like percent to molar solution or molar to molar etc. If you'd like to try it out the address is
www.cleanroom.byu.edu/MolestoAnything.phtml
Just for future reference if you ever need it.
Krysia