Question

What do you do when pH is already measured and you need to convert from pH to the amount concentration of hydronium ions? a) Multiply by 10

b) Divide by 10
c) Raise 10 to the power of the negative pH value
d) Subtract 10 from the pH value

Answer 1

To convert pH to hydronium ion concentration, raise 10 to the power of the negative pH value and round according to significant figures. Option c.

Step-by-step explanation:

To convert a pH value to the amount concentration of hydronium ions ([H3O+]), you should raise 10 to the power of the negative pH value. For instance, if you have a pH value of 7.04, you would first multiply this by (-1) to obtain -7.04. Then you take the antilog (or inverse log) of this by raising 10 to the power of -7.04.

Using a calculator, you would get approximately 9.120108 × 10-8, and after rounding according to significant figures from the pH value, you would get an answer of 9.1 × 10-8 M for the hydronium ion concentration. Option c.