Question

Write a reaction of NH3 (a weak base) with water. Circle the substance in the reaction that is acting as an acid. Underline the conjugate base and put a box around the conjugate acid. Write the Kb expression for NH3.

Answer 1

The reaction for ammonia with water are as follows:-

NH₃ (aq) + H₂O (l) $\rightleftharpoons$ NH₄⁺ (aq) + OH^- (aq)

Since in above reaction NH₃ is a base and according to the definition, a base is a substance which accepts a proton. Therefore the base form its acid which is NH₄⁺ and OH^- will acts as conjugate base.

The Kb expression will be written as

product Kb = Reactar

Therefore the K_b expression for above reaction will be

[NH4+][OH-1 (NH3)

Here water is present in large amount so we consider that its concentration is 1.

If you find any mistake please mention in the comment box.

Thanks.