Download Chemistry Exam Document for Third Year - Physical Chemistry (CHEMISTRY CH301) - Semester 2 and more Exams Physical Chemistry in PDF only on Docsity! Page 1 of 5 Semester 2 Examinations 2010 Exam Code(s) CHEMISTRY CH301 Exam(s) Third Year Chemistry Module Code(s) CH313 Module(s) PHYSICAL CHEMISTRY Paper No. 1 Repeat Paper External Examiner(s) Prof. Paul Seakins Internal Examiner(s) Prof. P. Murphy, Dr. W. M. Carroll, Dr. H. Curran, Dr. D. Leech, Dr. A. Ryder Instructions: ANSWER FOUR (4) QUESTIONS ONE FROM EACH SECTION Duration: Two (2) Hours No. of Pages 5 Department(s) Chemistry Course Co-ordinator(s) Dr. H. Curran Requirements: MCQ Release to Library: Yes ' No ' Statistical/ Log Tables x Graph Paper x Gas constant, R = 8.3143 J K–1 mol–1 Avogadro constant, NA = 6.022 × 1023 mol–1 Planck constant, h = 6.624 × 10–34 J s Velocity of light, c = 2.998 × 108 m s–1 Electronic charge, e = 1.602 × 10–19 C Boltzmann constant, k = 1.381 × 10–23 J K–1 Electronic mass, m = 9.109 × 10–31 kg Bohr magneton, µB = 9.274 × 10–24 J T–1 Faraday constant, F = 96,485 C mol–1 1 atmosphere = 101,325 N m–2 Page 2 of 5 Section A 1. Define the term lattice enthalpy. [5 marks] Calculate the lattice enthalpy at 298 K of CaCl2, defined as: CaCl2 (s) = Ca2+ (g) + 2Cl– (g) using the following data. The enthalpy of formation of CaCl2 (s) is –795.8 kJ mol-1. Reaction Enthalpy of reaction, ∆HӨ / kJ mol–1 Ca (s) = Ca (g) 178.2 Ca (g) = Ca2+ (g) 1740.0 Cl2 (g) = 2Cl (g) 241.6 Cl (g) = Cl– (g) – 364.9 [10 marks] Given the equation for the potential energy of interaction between two dipoles is: Define all the terms in the equation above and calculate the molar potential en- ergy of the dipolar interaction between two peptide links separated by 3.5 nm, in different regions of a polypeptide chain with θ = 150o, µ1 = µ2 = 2.6 D. [10 marks] 2. The following is a diagram of a representation of a gas flow through a plug-flow reactor: where [A]i = inlet concentration of A, [A]o = outlet concentration of A, V is the volume of the reactor and υ is the volume flow rate or flow velocity. Derive the following equation for the dependence of the concentrations on the flow rate for a 1st-order reaction in a plug-flow reactor: −= υ Vk i]A[ ]A[ln o [10 marks] Peracetic acid vapour at 2% by volume in nitrogen carrier gas at a total pressure of 101 kPa and 490 K flows through 1.4 mm radius Teflon tubing and is sampled 1.2 m downstream with the following results: ([A]o/[A]i) 0.346 0.578 0.718 ν (m3 s−1) 3.71 × 10–5 7.20 × 10–5 1.19 × 10–4 Show that reaction follows first order kinetics and calculate the rate constant, k. [15 marks] [A]o[A]i V dV 3 0 2 21 4 )cos31( r V πε θµµ − −=
