[sdhetzler@aol.com]

30 mL of .10M NaOH neutralized 25.0mL of hydrochloric acid. determine the concentration of the acid..
Please help

[Hunter2]

What does the M tells you? If you know this you can find out how many moles in 30 ml.
Write down neutralization equation. You can see how many mole NaOH correspond to how many mole HCl. The amount of NaOH you calculate back to the concentration.

[Borek]

http://www.titrations.info/titration-calculation

[Arkcon]

What volume and concentration would neutralize 30 mL of 1 M NaOH?  What if it took 60 mL, then wouldn't it be twice as weak?  Or if it took 2/3 the volume?  Or twice the volume?

These are questions you can ask yourself, to help you learn how to solve these sorts of problems.  You will not get the exact same numbers in an exam question, so you will have to be able to figure it out.

This is how we help on these forums, we give you hints, to help yourself.  Read the Forum Rules{click}.