Practice Problems

Convert each hydrogen ion concentration into a pH. Identify each as an acidic pH or a basic pH.

1) 0.0015

pH = - log 0.0015
pH = - (- 2.82)
pH = 2.82
acidic

2) 5.0 x 10¯9

pH = - log 5.0 x 10¯9
pH = - log (- 8.30)
pH = 8.30
basic

3) 1.0

pH = - log 1.0
pH = - (0)
pH = 0.00
acidic

Yes, a pH of zero is possible, it is just uncommon. In fact, watch out for this teacher test trick. What's the pH when [H+] = 2.0 M? That's right, NEGATIVE 0.30. It is possible to have a negative pH, it is just real uncommon to see them.

4) 3.27 x 10¯4

pH = - log 3.27 x 10¯4 = 3.489. acidic.

5) 1.00 x 10¯12

pH = - log 1.00 x 10¯12 = 12.000. basic.

6) 0.00010

pH = - log 0.00010 = 4.00. acidic.

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