The weak base ammonia, NH3, and the strong acid hydrobromic acid react to form the salt ammonium bromide, NH4Br. Given that the

Question

2 years ago

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value of Kb for ammonia is 1.8×10−5, what is the pH of a 0.053 M solution of ammonium bromide at 25∘C?

1 answer:

Leya [2.2K] · Answer 1 · 2023-12-22T00:57:57+03:00

The pH of a 0.053 M solution of ammonium bromide at 25° C is equal to 33.9.

<h3>What are acids and bases?</h3>

Acids are a substance that has a pH lower than 7 and bases are a substance that has a pH of more than 7.

the pH of any solution will be calculated as:

pH = -log[H⁺]

Given the chemical reaction in equilibrium with ICE table will be:

NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺

Initial: 0.289 0 0

Change: -x +x +x

Equilibrium: 0.289-x x x

Equation for Kb for this reaction is:

Kb = [NH₃][H₃O⁺] / [NH₄⁺]

Given value of Kb = 1.8 × 10⁻⁵

On putting values equation becomes

1.8 × 10⁻⁵ = x² / 0.053 - x

The value of x is negligible as compared to 0.053 so the equation becomes

1.8 × 10⁻⁵ = x² / 0.053

x = 2.28 × 10⁻³

i.e. [NH₃] = [H₃O⁺] = 33.9 × 10⁻³

Calculating the pH by putting this concentration value on the equation

pH = -log(33.9 × 10⁻³)

pH = 33.9

Thus, the pH will be 33.9.

To learn more about acids and bases, refer to the link:

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