What determines the pH of a buffer solution? (2 marks)
CHEMISTRY, M6 EQ-Bank 29
Explain why a mixture of acetic acid (1 M) and sodium acetate (1 M) can act as a buffer while a mixture of hydrochloric acid (1 M) and sodium chloride (1 M) cannot. (3 marks)
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CHEMISTRY, M6 2018 HSC 17 MC
Increasing amounts of carbon dioxide were dissolved in two beakers, one containing water and one a mixture of water and a buffer. The pH in each beaker was measured and the results graphed.
Which graph best represents the results?
CHEMISTRY, M6 2018 HSC 15 MC
A solution containing potassium dihydrogen phosphate and potassium hydrogen phosphate is a common laboratory buffer with a `text{pH}` close to 7.
Which row of the table correctly identifies the chemistry of this buffer?
CHEMISTRY, M6 2015 HSC 24
- Explain why the salt, sodium acetate, forms a basic solution when dissolved in water. Include an equation in your answer. (2 marks)
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- A solution is prepared by using equal volumes and concentrations of acetic acid and sodium acetate.
- 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. (3 marks)
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CHEMISTRY, M6 2017 HSC 14 MC
One litre of an aqueous solution is formed from mixing equal volumes of 0.2 mol L¯1 hydrochloric acid `text{(HCl)}` and 0.2 mol L¯1 sodium chloride \(\ce{(NaCl)}\).
How effective as a buffer is the aqueous solution formed?
- Ineffective, because `text{HCl}` is a strong acid
- Effective, because \(\ce{Cl-}\) is the conjugate base of \(\ce{HCl}\)
- Ineffective, because \(\ce{NaCl}\) forms a neutral salt solution
- Effective, because the pH would change when a solution of \(\ce{NaOH}\) is added
CHEMISTRY, M6 2019 HSC 22
A buffer was prepared with acetic acid and sodium acetate. A few drops of universal indicator were then added. When small amounts of either 0.1 mol L ¯1 \(\ce{HCl(aq)}\) or 0.1 mol L ¯1 \(\ce{NaOH(aq)}\) were added, no change in the colour of the solution was observed.
Explain these observations. Support your answer with at least ONE chemical equation. (4 marks)
CHEMISTRY, M6 2020 HSC 8 MC
CHEMISTRY, M6 2021 HSC 34
Gaseous `text{HCl}` was bubbled into water and two solutions, `X` and `Y`. Solutions `X` and `Y` contain the same type of ions. The pH of each was monitored over time and recorded in the graph shown.
Explain the observed pH of the water and each of the solutions at `t_0, t_1` and `t_2`. Include a relevant balanced chemical equation in your answer. (5 marks)