12.67 Calculating pH from Molarity and Formula

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HoganFenster2E
Posts: 23
Joined: Fri Sep 25, 2015 3:00 am

12.67 Calculating pH from Molarity and Formula

Postby HoganFenster2E » Tue Nov 24, 2015 3:38 pm

For question 12.67 in the homework, when you are given the molarity and molecular formula, how are we supposed to go about ranking the pH. I was thinking the ice box however the solutions manual does not do this. It seems like it does it a much easier way. Can you rank the pH's just by looking at the molarities and formula?
Given:
1x10^-5 M HCL
0.20 M CH3NH3Cl
0.20 M CH3COOH
0.20 M C6H5NH2

Chloe 3D
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

Re: 12.67 Calculating pH from Molarity and Formula

Postby Chloe 3D » Tue Nov 24, 2015 4:01 pm

I think you use the molecular formula to determine whether each compound is an acid or a base. From there, you can take the negative log of the molarities to find the pH (if the compound is an acid) or the pOH (if the compound is a base). Once you have the pOH, subtract this value from 14.00 to find the pH of the base.


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