Question

Can someone please help me with these questions? Please write out the steps as well so that i understand it best. Thank you!

1. A solution of acetic acid is 28.5% deprotonated. What is the pH of the solution if the pK_a for acetic acid is 4.76? 2. 20 mL of 2.00 M HNO₃ is added to 100 mL of 0.15 M NaOH. What is the final pH of the solution?

3. A solution of carbonic acid (H₂CO₃) has a pH of 5.55. If the pK_a of carbonic acid is 6.35, what is the ratio of protonated to deprotonated carbonic acid molecules? Use three significant figures in your answer.

4.What is the pH of a solution that contains 20.0% acetic acid and 80.0% sodium acetate (pKa for acetic acid in 4.76)? Make sure to use the correct number of significant figures.

5.At pH 3.0, what percentage of lactic acid is in its deprotonated form (pka for lactic acid is 3.86)? Make sure to use the correct number of significant figures, do not include the % sign in your answer.

Answer 1

ANSWER 1 :-

According to the Henderson-Hasselbalch equation :-

pH = pKa + log [A^-] / [HA]

pH = pKa + log [CH₃COO^-] / [CH₃COOH]

pH = 4.76 + log [28.5] / [71.5]

pH = 4.76 + log [0.39]

pH = 4.76 + (-0.40)

pH = 4.76 - 0.40

pH = 4.36

According to the data provided, the acid is 28.5 % deprotonated. This can be stated as the [A-] value. When the pH value is less than the pKa value, the acid shows more protonation than deprotonation.

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