Question

The degree to which a weak base dissociates is given by the base-ionization constant, Kb. For the generic weak base, B

B(aq)+H2O(l)⇌BH+(aq)+OH−(aq)

this constant is given by

Kb=[BH+][OH−][B]

Strong bases will have a higher Kb value. Similarly, strong bases will have a higher percent ionization value.

Percent ionization=[OH−] equilibrium[B] initial×100%

Strong bases, for which Kb is very large, ionize completely (100%). For weak bases, the percent ionization changes with concentration. The more dilute the solution, the greater the percent ionization.

Ammonia, NH3, is a weak base with a Kb value of 1.8×10−5.

Part A

What is the pH of a 0.185 M ammonia solution?

Express your answer numerically to two decimal places.

Hints

pH =

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Part B

What is the percent ionization of ammonia at this concentration?

Express your answer with the appropriate units.

Hints

% ionization =

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Answer 1