A patient with respiratory alkalosis has a blood plasma pH of 7.54. What is the [OH−] of the blood plasma? Express your answer to two significant figures and include the appropriate units.

Answer 1

Two different ways to answer this:

pH = 7.54

pH = -log [H⁺]

[H⁺] = 1x10^-7.54

[H⁺] = 2.88x10^-8 M

[H⁺][OH^-] = 1x10^-14

[OH^-] = 1x10^-14 / 2.88x10^-8

[OH^-] = 3.47x10^-7 M (2 sig. figs. b/c when taking logs, decimal places are the sig. figs.)

pH + pOH = 14

pOH = 14 - 7.54

pOH = 6.46

[OH-] = 1x10^-6.46

[OH-] = 3.47x10^-7