# Logarithmic scale for pH: how many times more acid is pH 5.2 than pH 6.5?

#### tambaqui

##### New member
Hi, my question is about the logarithmic scale used for pH.
I know pH 5 is 10 times more acid than pH 6 and 100 times more acid than pH 7.
What about fractions of pH values?
Is pH 4.5 actually 50 times more acid than ph 6?
I need to know...how many times more acid is pH 5.2 than pH 6.5?
I would really appreciate any help on this.
Thank you.

Staff member

#### tambaqui

##### New member
Logarithmic scale for pH 2

Check out this short example, and let us know if you have any more questions.
Hi, thank you so much for the reply.
The equation makes sense. When I do the example I get the same answer. Also when I use whole integers I get the correct answer (pH5 is 10 times more acid than ph6) but when I tried my numbers comparing pH 5.2 and 6.5, it doesn't seem to work.
See below:
10[SUP]-5.2[/SUP] = 6.31 x 10[SUP]-6[/SUP]
10[SUP]-6.5[/SUP] = 3.16 x 10[SUP]-7[/SUP] = 31.6 x 10[SUP]-6[/SUP]

6.31/31.6 = 0.1997

I don't know what I'm doing wrong (feeling kind of stupid). pH 5.2 should be about 50 times more acid than 6.5 right (pH5 is 100 x more acid than pH7)??

#### stapel

##### Super Moderator
Staff member
10[SUP]-5.2[/SUP] = 6.31 x 10[SUP]-6[/SUP]
10[SUP]-6.5[/SUP] = 3.16 x 10[SUP]-7[/SUP] = 31.6 x 10[SUP]-6[/SUP]
3.16 * 10^(-7) = 0.000000316

31.6 * 10^(-6) = 0.00000316

They're not equal. Did you perhaps mean to convert as follows?

6.31 * 10^(-6) = 63.1 * 10^(-7)

#### tambaqui

##### New member
Logarithmic scale for pH: how many times more acid is pH 5.2 than 6.5? answer: 19.97

3.16 * 10^(-7) = 0.000000316

31.6 * 10^(-6) = 0.00000316

They're not equal. Did you perhaps mean to convert as follows?

6.31 * 10^(-6) = 63.1 * 10^(-7)

thank you, I got 19.97 for an answer.