What is the pH of a 1.0x10−5 M solution of NaOH?

1 Answer
anor277
Dec 2, 2016

In water pH+pOH=14

pH=14−pOH=14−5=9

Explanation:

pOH=−log10[HO−] by definition.

Thus pOH=−log10(1×10−5)=−(−5)=5

pH+pOH=14

pH=14−pOH=14−5=9

When we write logab=c, we ask to what power we raise the base, a, to get b; here ac=b. The normal bases are 10, (common logarithms), and e, (natural logarithms).

Thus when we write log10(10−5), we are asking to what power we raise 10 to get 10−5. Now clearly the answer is −5, i.e. log10(10−5)=−5, alternatively log10(105)=+5.

What are log10(100),log10(1000),log10(1000000)??

You shouldn't need a calculator, but use one if you don't see it straight off.

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