Question

What are the concentrations of hydroxide and hydronium ions in a solution with a pH of 4.6?

1.3 × 10–4 M H3O+ and 7.7 × 10–11 M OH–

2.5 × 10–5 M H3O+ and 4.0 × 10–10 M OH–

7.9 × 10–6 M H3O+ and 1.3 × 10–9 M OH–

8.7 × 10–7 M H3O+ and 1.1 × 10–8 M OH–

Answer 1

2.5 × 10–5 M H3O+ and 4.0 × 10–10 M OH–

Answer 2

2.5 × 10–5 M H3O+ and 4.0 × 10–10 M OH–

Step-by-step explanation:

pH = - log[H3O+]

Therefore;

pH = - log[H3O+] = 4.6

Hence;

[H3O+] = 10^-4.6

= 2.51 ×10^-5 M

= 2.5 ×10^-5 M

Additionally;

pH + pOH = 14

Thus; pOH = 14 -pH

= 14 -4.6

= 9.4

but; pOH = - log [OH-]

Therefore;

[OH-] = 10^-9.4

= 3.98 × 10^-10 M

= 4 × 10^-10 M