Ammonia, nh3, is a weak base with a kb value of 1.8*10-5. part a what is the ph of a 0.440 m ammonia solution? express your answer numerically to two decimal places. view available hint (s)

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Chemistry

Davis Clay

18 September, 22:03

Ammonia, nh3, is a weak base with a kb value of 1.8*10-5. part a what is the ph of a 0.440 m ammonia solution? express your answer numerically to two decimal places. view available hint (s)

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Answers (1)

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Isabela Maynard · Answer 1

Answer is: pH of ammonia solution is 11,43.

Chemical reaction of ammonia in water: NH ₃ + H₂O → NH₄⁺ + OH⁻.

Kb (NH ₃) = 1,8·10⁻⁵.

c ₀ (NH₃) = 0,44 M = 0,44 mol/L.

c (NH ₄⁺) = c (OH⁻) = x.

c (NH ₃) = 0,44 mol/L - x.

Kb = c (NH ₄⁺) · c (OH⁻) / c (NH₃).

0,000018 = x² / (0,4 mol/L - x).

x² + 0,000018x - 0,0000072 = 0.

solve quadratic equation: x = c (OH⁻) = 2,67·10⁻³ mol/L.

pOH = - log (2,67·10⁻³ mol/L) = 2,57.

pH = 14 - 2,57 = 11,43.