Simple dilution question

[BrightSmile]

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Hello, Yes I say simple, but obviously I am missing something to have to ask how to get the right answer to this question. I did a search first and could not find an answer that would help me. It could be that my test is a week away and my brain is freaking out. This is from a Kaplan practice test.

"Concentrated sulfuric acid is 18M. What volume of water would be needed to dilute 25mL of concentrated H2SO4 solution to 3M?"
Ans: 125 mL.

I thought this was a simple M1V1=M2V2, but that gets me 150mL. Could someone please advise where I am making my mistake?
Thanks so much!

 

[bigbevo34]

150 mL is the TOTAL volume of the new solution. You have to be careful of what the question is actually asking for.

Volume of H20 = total volume (150 mL) - volume of acid (25 mL) = 125 mL

 

[BrightSmile]

AUUUUGGHHH!
I know I am going to make stupid mistakes like this the day of the test!
Thank you for pointing that out!