Question

When a 0.089M aqueous solution of a certain acid is prepared, the acid is 12.% dissociated. Calculate the pH of the solution. Round your answer to 2 decimal places.

Answer 1

To determine the pH of a 0.089M solution of an acid that is 12% dissociated, we first calculate the hydronium ion concentration and then use the formula for pH. After calculation, the pH is found to be 2.97.

Step-by-step explanation:

To calculate the pH of the solution where the acid is 12% dissociated, we first need to determine the concentration of hydronium ions ([H+]) in the solution.

Given a 0.089M solution of an acid that is 12% dissociated, the concentration of dissociated hydronium ions is:

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This concentration has three significant figures. Using the formula for pH which is:

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The pH is then calculated as:

pH = -log(0.01068) = 2.97

The result is in the acidic pH range, and it has been rounded to two decimal places to match the number of significant figures from the initial concentration given.

Answer 2

pH = 1.98

Step-by-step explanation:

Given a general acid dissociation:

HA + H₂O ⇆ H₃O⁺ + A⁻

The pH is -log[ H₃O⁺ ]

Therefore we need to determine [ H₃O⁺ ] to answer this question, and we should use the data of % dissociation of the acid.

Percent dissociation is

% dissociation = [ H₃O⁺ ] / [ HA ]₀ x 100

where [ HA ]₀ is the original acid concentration, so we can calculate [ H₃O⁺ ] , and then the pH.

12 = [ H₃O⁺ ] /0.089 M ⇒ [ H₃O⁺ ] = (12 x 0.089 /100) M

= 1.07 x 10⁻² M

and pH = - log ( 1.07 x 10⁻² ) = 1.98