JPJC 2026 Chemical Energetics Assignment

2026 JPJC JC1 H2 Chemistry (9476) 1 [Turn Over JURONG PIONEER JUNIOR COLLEGE 2026 JC1 H2 Chemistry (9476) Topical Assignment Topic 5: Chemical Energetics (Part 1 and 2) Name : __________________________________________ Penalty: ‒1 / NA * o Incorrect significant figures in final answer o Missing/incorrect units in final answer (* delete accordingly) 15 Class : 26S ___ Date : ____________ Duration : 25 minutes 1 (a) By using relevant data from the Data Booklet and the data given in Table 1.1, draw a Born‒Haber cycle on the grid below and use it to calculate the enthalpy change of formation of solid iron(II) bromide. Table 1.1 electron affinity of bromine, Br(g) + e‒ → Br ‒(g) ‒325 kJ mol‒1 enthalpy change of atomisation of Br2(l) +112 kJ mol‒1 enthalpy change of atomisation of Fe(s) +350 kJ mol‒1 lattice energy of FeBr2(s) ‒2577 kJ mol‒1 Hf(FeBr2(s)) = …………...…………………………………………………………..………. [4] Enthalpy / kJ mol −1 0

2026 JPJC JC1 H2 Chemistry (9476) 2 (b) Suggest and explain how you would expect the magnitude of the lattice energy of iron(II) oxide, FeO, to compare with that of iron(II) bromide, FeBr2. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… [2] (c) Using relevant data in Table 1.1 and data in Table 1.2, construct an energy cycle and use it to calculate the enthalpy change of solution of iron(II) bromide. Table 1.2 Enthalpy change of hydration of Fe2+ ion ‒1950 kJ mol‒1 Enthalpy change of hydration of Br ‒ ion ‒348 kJ mol‒1 [2] (d) Using relevant data from the Data Booklet, suggest and explain how you would expect the numerical value of the standard enthalpy change of hydration of Mg2+ to compare with that of Fe2+. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… [2] [Total: 10]

2026 JPJC JC1 H2 Chemistry (9476) 3 [Turn Over 2 Table 2.1 lists two Hf values. Table 2.1 compound Hf / kJ mol‒1 NO2(g) +33.2 N2O5(g) +5.0 (a) The standard Gibbs free energy change of formation of NO2(g) is +51.3 kJ mol−1. Calculate Sf of NO2(g). [1] (b) The enthalpy change for the dissociation of N2O5(g) is given below. reaction 1: N2O5(g) → NO2(g) + NO3(g) H1 = +92.5 kJ mol‒1 (i) Use the given H1 value and data in Table 2.1 to calculate Hf of NO3(g). [1] (ii) Predict the sign of ∆S for reaction 1, showing your reasoning. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [1] (iii) By considering the entropy and enthalpy changes, explain why reaction 1 is favoured by a high temperature. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [1]

2026 JPJC JC1 H2 Chemistry (9476) 4 (c) N2O5 can be decomposed to give NO2 and O2 according to reaction 2. reaction 2 2N2O5(s) → 4NO2(g) + O2(g) H2 = +110 kJ mol‒1 The standard entropy change of reaction 2 is +470 J mol–1 K–1. Calculate the minimum temperature (to the nearest Kelvin) above which the reaction 2 becomes spontaneous. [1] [Total: 5]