A solution of ammonia has a pH of 11 point 8 What is the concentration of OH raised to the negative power ions in the solution? Useful formulas include open bracket cap h sub 3 cap o raised to the plus power close bracket is equal to 10 raised to the negative pH power , open bracket OH raised to the negative power close bracket is equal to 10 raised to the negative pOH power , pH plus pOH is equal to 14 and open bracket cap h sub 3 cap o raised to the plus power close bracket times open bracket OH raised to the negative power close bracket is equal to 10 to the negative 14 power
Answer
A
158 cap m
B
2 point 2 0 cap m
C
6 point 3 1 times 10 to the negative 3 power cap m
D
1 point 5 8 times 10 to the negative 12 power cap m
Explanation
Use pH + pOH = 14: pOH = 14 − 11.8 = 2.2. Then [OH⁻] = 10⁻ᵖᴼᴴ = 10⁻²·² ≈ 6.31 × 10⁻³ M. Therefore, the hydroxide ion concentration is 6.31 × 10⁻³ M, choice D.
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