NYJC_2023_H2_Chemistry_9729_P2_Answer

Nanyang Junior College 2023 J2 H2 Chemistry Prelim Exam Answers 1 H2 Chemistry Prelim Exam Answers Paper 2 Answers 1 (a) (i)     3 3 3 NOC 125 101325 8.31 150 273 3603 mol m 3603 mol dm1000 3 60 mol dm pV nRT np V RT           . l (ii) The pressure of NOC l is very high, causing the volume of NOC l gas particles to become more significant relative to the total volume of the gas. There is significant intermolecular forces of attraction (i.e. permanent dipole - permanent dipole or instantaneous dipole-induced dipole interactions between NOCl molecules) as it is polar/has a relatively large electron cloud size.

Nanyang Junior College 2023 J2 H2 Chemistry Prelim Exam Answers 2 (b) (i) (ii) The graph is straight line passing through origin, rate increases linearly with (ρNOCl)2. The order of reaction with respect to ρNOCl is 2. (iii) Rate = k(ρNOCl)2 Units: N-1 m2 s-1 Initial rate / N m-2 s-1 (ρNOCl)2 / N2 m-4 0.20 0.40 0.60 0.80 1.00 50 100 150 200 x x x x x

Nanyang Junior College 2023 J2 H2 Chemistry Prelim Exam Answers 3 (c) Increasing temperature will lead to  an increase in the average kinetic energy of reactant molecules,  more molecules will have energy greater or equal to Ea.  frequency of effective collisions increases.  rate of reaction increases,  hence the rate constant increases (since rate = k[conc] and [conc] is unchanged). (d) rate = k[Cl2][NO]2 2 (a) (i) Lattice energy is the energy evolved when one mole of an ionic compound is formed

Nanyang Junior College 2023 J2 H2 Chemistry Prelim Exam Answers 4 from its constituent gaseous ions under standard condition. (ii) Ionic radius of Cl─ ion = 0.181 nm Ionic radius of I─ ion = 0.216 nm Ionic radius of Cl─ ion is smaller than the ionic radius of I─ ion. Since Cl─ ion in Ag Cl and I─ ion in AgI have the same ionic charge, the theoretical lattice energy of AgCl is more exothermic than the theoretical lattice energy of AgI. (iii) Ag+ has high charge density and hence high polarising power. It can distort the electron cloud of Cl─ ion to result in sharing of electron density. This results in covalent character in the ionic bonds of AgCl. (iv) AgI has greater covalent character as I─ has a larger and more polarisable electron cloud. (b) (i) ( ( (- (  ─ ( ( ( (  ─ (ii) By Hess’s L w, ∆Hf = (+178) + (+½ x 244) + (+590) + (349) + (687) = 146 kJ mol─1 (iii)

Nanyang Junior College 2023 J2 H2 Chemistry Prelim Exam Answers 5 y 2CaCl(s) Ca(s) + CaCl2(s) From