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24. (a) Explain why the salt, sodium acetate, forms a basic solution when dissolved in water - HSC - SSCE Chemistry - Question 24 - 2015 - Paper 1
Question 24
24. (a) Explain why the salt, sodium acetate, forms a basic solution when dissolved in water. Include an equation in your answer. (b) A solution is prepared by usi... show full transcript
Worked Solution & Example Answer:24. (a) Explain why the salt, sodium acetate, forms a basic solution when dissolved in water - HSC - SSCE Chemistry - Question 24 - 2015 - Paper 1
Step 1
Explain why the salt, sodium acetate, forms a basic solution when dissolved in water. Include an equation in your answer.
Answer
Sodium acetate (CH₃COONa) is the sodium salt of acetic acid. When dissolved in water, it dissociates into sodium ions (Na⁺) and acetate ions (CH₃COO⁻). The acetate ion can undergo hydrolysis with water, producing hydroxide ions (OH⁻):
As a result of this reaction, the concentration of hydroxide ions increases in the solution, which contributes to the basic nature of the resulting solution.
Step 2
Explain how the pH of this solution would be affected by the addition of a small amount of sodium hydroxide solution. Include an equation in your answer.
Answer
When a small amount of sodium hydroxide (NaOH) is added to the solution containing equal parts of acetic acid and sodium acetate, it dissociates completely in solution to yield hydroxide ions (OH⁻):
The increase in OH⁻ concentration affects the equilibrium established by the acetate ion and water. According to Le Chatelier's principle, the system will shift to the left to counteract the increase in OH⁻, consuming the acetic acid (CH₃COOH) and producing more acetate ions (CH₃COO⁻):
This results in minimal change in the pH, as the buffer system resists drastic alterations. However, a slight increase in pH will occur due to the additional hydroxide ions.