pH ratio question

[BWM95]

Can someone just explain to me how you know to divide 1/100, instead of 100/1 like I did?

I knew that B and C are wrong, & and I understand that there is a 100x difference in [H+]

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[BWM95]

Do you always put the smaller number on top of the ratio?

 

[BerkReviewTeach]

The question boils down to a ratio of [H+] at pH = 6 to [H+] at pH = 4. The 100 part comes from the log scale (which you clearly got right). The next step is to consider whether there is more hydronium at pH = 4 or pH = 6. The lower pH has greater [H+], so the correct answer is a ratio of (a smaller number) : (a bigger number), so it must be 1 : 100.

The fraction must be set up in the ration described in the passage.

 

[BWM95]

The question boils down to a ratio of [H+] at pH = 6 to [H+] at pH = 4. The 100 part comes from the log scale (which you clearly got right). The next step is to consider whether there is more hydronium at pH = 4 or pH = 6. The lower pH has greater [H+], so the correct answer is a ratio of (a smaller number) : (a bigger number), so it must be 1 : 100.

The fraction must be set up in the ration described in the passage.

I cant believe I didnt realize that, thanks so much for the help!


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[aldol16]

Instead of remembering which one to put on top, it's easier to just convert the question stem into an equation.

Ratio of A-to-B means A/B.

Therefore, ratio of [H+] at pH 6 (highest activity) to [H+] at pH 4 (lowest activity) is given by the pH equation. That is, 10^-pH = [H+].

Thus, this reduces to 10^-6/10^-4, which if you remember the rules for division of exponentials, is 10^-2.

 

[BWM95]

Instead of remembering which one to put on top, it's easier to just convert the question stem into an equation.

Ratio of A-to-B means A/B.

Therefore, ratio of [H+] at pH 6 (highest activity) to [H+] at pH 4 (lowest activity) is given by the pH equation. That is, 10^-pH = [H+].

Thus, this reduces to 10^-6/10^-4, which if you remember the rules for division of exponentials, is 10^-2.

That makes sense, thanks I appreciate it!


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