In the extraction of Fe(III) into diethyl ether, it is desired that the final acid concentration should be 1.0 M to 25 mL of the iron solution prepared in 1.0 M HCl. What volume of 12.0 M HCl should be added so that the final strength becomes 7.0 M?

1 Answer
May 2, 2016

30mL

Explanation:

The question is not clear enough

I proceed as I understand.
Initial volume of acid is
V_1=25mL

Initial strength of acid is
S_1=1M

Let xmL of 12M HCl to be added with 25mL 1M HCl to have (25+x)mL 7M final solution

So V_2=xmL and S_2=12ML

Again V_3=25+x mL and S_3=7M

So V_1S_1+V_2S_2=V_3S_3
=>25*1+x*12=(25+x)*7
=>5x=150
=>x=30mL