[H3O+]=4.2×10−8M, [H3O+]=4.7×10−2M , [H3O+]=4.7×10−2M, [OH−]=0.006M

Question

Determine PH, Express your answer using two decimal places.

Answer 1

These are the relationships you need to know:

pH = -log [H₃O⁺]

pOH = -log [OH^-]

pH + pOH = 14

[H₃O⁺][OH^-] = 1x10^-14

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[H3O⁺] = 4.2x10^-8 M

pH = - log 4.2x10^-8

pH = 7.38

[H₃O⁺] = 4.7x10^-2 M

pH = -log 4.7x10^-2

pH = 1.33

[OH^-] = 0.006 M

pOH = -log 0.006

pOH = 2.22

pH + pOH = 14

pH = 14 - pOH = 14 - 2.22

pH = 11.78