6B. 3 Volume

Ariel Fern 2B
Posts: 90
Joined: Fri Aug 30, 2019 12:17 am

6B. 3 Volume

What volumes did you use to get the pH's in this problem? Wouldn't it be 0.200 L and 0.250 L due to the volumetric flasks? I'm not getting the correct pH's using those numbers though, so any help would be appreciated!

Gerald Bernal1L
Posts: 87
Joined: Thu Jul 11, 2019 12:16 am

Re: 6B. 3 Volume

To find the desired pH you just use the desired concentration 0.025 and you get pH of 1.6. To get the actual solution pH you multiply the molarity by the 0.200 L volume in order to find the desired moles and divide that by 0.250 L to get the new molarity/H3O+ concentration. From there you put that in the pH equation and you get pH of 1.7.

Ariel Fern 2B
Posts: 90
Joined: Fri Aug 30, 2019 12:17 am

Re: 6B. 3 Volume

Gerald Bernal1L wrote:To find the desired pH you just use the desired concentration 0.025 and you get pH of 1.6. To get the actual solution pH you multiply the molarity by the 0.200 L volume in order to find the desired moles and divide that by 0.250 L to get the new molarity/H3O+ concentration. From there you put that in the pH equation and you get pH of 1.7.

Thanks so much, Gerald! That makes much more sense, lol; I think I misread the problem on accident and thought they were diluting the 0.025 M solution by using the volumetric flask to fill it up to 0.200 L and 0.250 L. I didn't realize that 0.025 M was the desired molarity of the solution.

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