McMaster University Chemistry Worksheet
The molar enthalpy of fusion of water is 6.02 kJ/mol at 0°C and the molar enthalpy of vaporization of water is 40.7 kJ/mol at 100°C. Determine the
entropy of fusion and entropy of vaporization for water. What is the standard entropy change of the reaction?
1.0 kg of air at pressure 1.73 MPa at 175°C expands isothermally to 3 times of its volume and then further expands adiabatically to 6 times of its original
volume. Isothermal compression is followed by adiabatic compression returns the air to its original state. R=0.29 kJ/kg*K, Gamma = 1.4. Determine the
pressure, volume, temperature at each corner of Carnot cycle, the Carnot efficiency of the cycle. (Hint V4/V1=V3/V2).
The thermal decomposition of phosphine (PH3) into phosphorus and molecular hydrogen is a first-order reaction:
4PH3(g) → P4 (g) + 6 H2 (g)
The half-life of the reaction is 25.0 s at 680°C. Calculate
a. The rate constant for the reaction
b. The time required for 95% of the phosphine to decompose
Using the initial rates method and the experimental data, determine the rate law and the value
of the rate constant for this reaction:
2NO(g) + Cl2(g) ⟶ 2NOCl(g)
5. The rate constant for the first-order decomposition of cyclobutane, C4H8 at 500 °C is 9.2 × 10−3 s−1:
C4 H8 ⟶ 2C2 H4
How long will it take for 80.0% of a sample of C4H8 to decompose?
6. The variation of the rate constant with temperature for the decomposition of HI(g) to H2(g) and I2(g) is
given here. What is the activation energy for the reaction?
7. The half–life of a reaction of compound A to give compounds D and E is 8.50 min when the initial concentration of A is 0.150 mol/L. How long will it take
for the concentration to drop to 0.0300 mol/Lif the reaction is (a) first order with respect to A or (b) second order with respect to A?