### 7th edition 6B.3

Posted:

**Tue Jan 15, 2019 11:12 am**I don't understand how to do part (b) of 6B.3 in the 7th edition with the 200ml value and 250ml value

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=49&t=39950

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Posted: **Tue Jan 15, 2019 11:12 am**

I don't understand how to do part (b) of 6B.3 in the 7th edition with the 200ml value and 250ml value

Posted: **Tue Jan 15, 2019 2:04 pm**

Hi! For 6B.3 use the 0.025M concentration given to find the desired pH with the formula pH=-log[H3O], since that is essentially the desired concentration. Then, to find the actual concentration in part b, use the equation M1V1=M2V2 with M1=0.025 M, V1=200 mL, V2=250 mL, and solve for M2. Finally, using this calculated concentration, you can use pH=-log[H3O] to calculate the actual pH of the solution.