(Transition metals, redox)
Answer: Increasing the pressure shifts the equilibrium position to the right (forward reaction) to decrease the pressure. This is because the forward reaction produces a fewer number of moles of gas (2 moles of NH₃) compared to the reactants (1 mole N₂ + 3 moles H₂ = 4 moles). Hence, the yield of ammonia increases.
For non-spontaneous: ΔG° > 0 ΔH° – TΔS° > 0 ⇒ –57,200 – T(–175.8) > 0 –57,200 + 175.8T > 0 175.8T > 57,200 T > 325.4 K (2 marks – inequality setup & final T) A Level H2 Chemistry 2021 Paper 3 Answers
: A notable question involved the solubility of NH4Clcap N cap H sub 4 cap C l , requiring students to relate Gibbs free energy ( ΔGcap delta cap G
Solidify knowledge of reaction mechanisms (nucleophilic substitution, electrophilic addition, etc.). For non-spontaneous: ΔG° > 0 ΔH° – TΔS°
Paper 3 (Free Response & Case Study) is designed to test a deep understanding of concepts rather than mere memorization. The 2021 paper was notable for its:
Divide the remaining moles by the total combined volume of the new mixture: You then subtract this from the initial amount
(multiplying by 2). You then subtract this from the initial amount of the conjugate base (e.g., cap F raised to the negative power ) to find the new equilibrium concentration. Electrochemistry