Calculating Water Needed for 0.1M and 0.12M Hydrochloric Acid

[josephcollins]

Could someone please give me a hand with this:

A solution of hydrochloric acid was standardised by titration and found to be 0.123 M. How much water must be added to 1dm3 of this solution to make it exactly:
a. 0.1M and b. 0.12M ?

Thanks ppl

 

[chem_tr]

Hello,

One liter of 0,123 M HCl means 0,123 mole of HCl is present in the solution. So if you want a) 0,1 M, you'll need to add: 0,1=(0,123/V)=1,23; and therefore 230 milliliters.

b) A 0,12 M of HCl solution from 0,123 M solution is prepared by adding: 0,12=0,123/V=1,025; and therefore, 25 milliliters of water.

Please note that you already have 1000 milliliters of solution, so the resulting new volume indicates the amount added, starting from 1000 milliliters.

Regards, chem_tr