A-Level Chemistry: Physical Chemistry Practice

Which of the following is always true for an exothermic reaction?

Using Hess’s Law, calculate the enthalpy of formation of CO(g) given: C(s) + O2(g) -> CO2(g), delta H = -393 kJ mol-1 and CO(g) + 0.5 O2(g) -> CO2(g), delta H = -283 kJ mol-1.

The standard enthalpy of atomisation of chlorine is +122 kJ mol-1. Use this to calculate the mean bond enthalpy of the Cl-Cl bond in Cl2.

Analyse the effect of increasing temperature on the rate of a chemical reaction using the Arrhenius equation.

A catalyst increases the rate of a reaction. Evaluate which statement correctly describes how a heterogeneous catalyst works.

Which of the following changes will shift the equilibrium position to the LEFT for the exothermic reaction: N2(g) + 3H2(g) <=> 2NH3(g), delta H = -92 kJ mol-1?

For the equilibrium: 2SO2(g) + O2(g) <=> 2SO3(g), Kc = 4.0 at temperature T. If [SO2] = 0.5 mol dm-3, [O2] = 0.25 mol dm-3, and [SO3] = 0.5 mol dm-3, calculate Qc and determine if the system is at equilibrium.

Evaluate the effect of adding an inert gas (e.g. argon) at CONSTANT PRESSURE on the equilibrium: PCl5(g) <=> PCl3(g) + Cl2(g).

Calculate the pH of a 0.050 mol dm-3 solution of HCl at 298 K. (HCl is a strong acid, fully dissociated.)

A weak acid HA has Ka = 3.2 x 10^-5 mol dm-3. Calculate the pH of a 0.10 mol dm-3 solution, assuming the approximation [HA]eq is approximately equal to [HA]init.

Analyse how a buffer solution resists changes in pH when a small amount of strong acid is added.

In a standard electrode potential measurement, what is the purpose of the standard hydrogen electrode?

Use Faraday’s laws to calculate the mass of copper deposited at the cathode when a current of 2.50 A is passed through CuSO4 solution for 45 minutes. (Cu = 63.5, F = 96500 C mol-1).

Evaluate the feasibility of the reaction: Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s) given E standard(Zn2+/Zn) = -0.76 V and E standard(Cu2+/Cu) = +0.34 V.