# ph question

Discussion in 'DAT Discussions' started by theedaddy77, Jun 3, 2008.

1. ### theedaddy77 2+ Year Member

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If you have 4m 40ml of Nitic acid and 2m 40ml of NaOH what is ph of final solution??????/
i know this sounds basic but if someone can explain how they got to there answer that would be amazing!!

2. ### TempleDMDKrazd 7+ Year Member

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are you talking about molality (m) or molarity (M)?

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3. ### doc toothache 10+ Year Member

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It will take 20 ml of 4 m nitric acid to neutralize 40ml of 2m NaOH, leaving 20ml of 4 m acid. Since the final volume will be 80 ml, then

m1v1= m2v2
4x20= m2x80
m2= 1
A 1 molar nitric will have a pH of zero.

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4. ### osimsDDS 5+ Year Member

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wow doc you just used plain old logic for that one i love it...faster and simpler than just plugging in numbers and doing a crap load of math, very nice

5. OP

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hey doc u did the last step by saying 1 M of a strong acid is 1M of H+ and -log 1 is 0?

6. ### doc toothache 10+ Year Member

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YES.
HNO3-----> H+ + NO3-
1m ...........1m....... 1m

Since nitric is 100% ionized 1m nitric= 1mH+

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