Advanced higher chemistry Unit2

When writing K for S(s) + O2(g) ⇌ SO2(g), how are pure solids treated?

• They are included with their measured concentrations.

• They are omitted because their concentrations are constant and set to 1.

• They are included only if present in excess.

• They are squared in the expression.

For the equilibrium N2O4(g) ⇌ 2 NO2(g) with ΔH = +ve, which change will increase the proportion of NO2 at equilibrium?

• Decreasing the temperature to 0°C

• Increasing the temperature to 80°C

• Adding a catalyst

• Removing NO2 as it forms

For endothermic forward reactions, how does increasing temperature affect the equilibrium constant K?

• K increases

• K decreases

• K stays the same

• K becomes undefined

Consider the equilibrium 2SO2(g) + O2(g) ⇌ 2SO3(g), ΔH is negative. If the temperature is increased, what happens to the position of equilibrium and the value of K?

• Shifts right; K increases

• Shifts right; K unchanged

• Shifts left; K decreases

• No shift; K unchanged

• 0

• 1

• −1

• 7

Which statement best describes the hydronium ion in aqueous solution?

• It is the same as a free H+ ion.

• It forms when H+(aq) coordinates to H2O to give H3O+(aq).

• It is produced only when bases react with water.

• It is neutral and has no charge.

Which equation represents the neutralisation of hydrogen and hydroxide ions in aqueous solution?

• H+(aq) + OH−(aq) → H2O(l)

• H+(aq) + H2O(l) → H3O+(aq)

• H2O(l) ⇌ H+(aq) + OH−(aq)

• H3O+(aq) + OH−(aq) → H2(g) + O2(g)

• K = [H3O+][OH−]

• K = [H3O+]/[OH−]

• K = [OH−]/[H3O+]

• K = [H2O]

Pure water autoionizes such that [H+] = [OH−]. What is the hydrogen ion concentration in pure water at 25 °C?

• 1.0 × 10−14 mol l−1

• 1.0 × 10−12 mol l−1

• 1.0 × 10−7 mol l−1

• 1.0 × 10−2 mol l−1

A 0.5 mol l−1 NaOH solution has [H+] = 2 × 10−14 mol l−1 at 25 °C. What is its pH (use pH = −log[H+])?

• 13.7

• 12.7

• 0.3

• 14.0