Advanced Higher Chemistry - Physical Chemistry

Which of the following salts will form a solution with the lowest pH?

• Potassium chloride

• Potassium ethanoate

• Ammonium chloride

• Ammonium ethanoate

Which of the following would not be suitable as a buffer solution?

• Boric acid and sodium borate

• Nitric acid and sodium nitrate

• Benzoic acid and sodium benzoate

• Propanoic acid and sodium propanoate

The reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) is reversible. After equilibrium has been established the reaction mixture was found to contain 0·2 moles of SO₂, 0·2 moles of O₂ and 16 moles of SO₃. Which of the following is correct?

• K > 1 and ∆G° > 0

• K > 1 and ∆G° < 0

• K < 1 and ∆G° > 0

• K < 1 and ∆G° < 0

2X(g) ⇌   Y(g)      ∆H = −220 kJ mol⁻¹

Which of the following changes will cause the equilibrium constant to increase?

• Decrease in temperature

• Increase in temperature

• Decrease in pressure

• Increase in pressure

HCN(aq) + H₂O(ℓ) ⇌ H₃O⁺ (aq) + CN⁻ (aq)

In the above equation HCN(aq) is acting as

• an acid

• a conjugate acid

• a base

• a conjugate base

Which of the equations shown represents the enthalpy of formation of a compound?

• A

• B

• C

• D

The use of an indicator is not appropriate in titrations involving

• hydrochloric acid solution and methylamine solution

• nitric acid solution and potassium hydroxide solution

• methanoic acid solution and ammonia solution

• propanoic acid solution and sodium hydroxide solution.

What is the concentration of hydroxide ions, in mol l^-1 , in a solution with a pH of 8·5?

• 8·5 × 10^-6

• 3·2 × 10^-6

• 8·5 × 10^-9

• 3·2 × 10^-9

Which of the following salts forms an alkaline solution in water?

• Sodium sulfate

• Lithium chloride

• Ammonium nitrate

• Potassium propanoate

The standard entropy of a perfect crystal is zero at

• O K

• 25 K

• 273 K

• 298 K