By Jamie Ross,2014-06-12 01:46
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    Class Name

    ID Number Total Points

    Tuesday July 11th 2006 Time: 110 Minutes 100 points total

    Number 1 2 3 4 5 6 7 8 9 10 Total


    Reviewer 1

    Reviewer 2

    Answer all questions in detail and SHOW ALL WORK!

    Please write answers on your answer-paper.

1. To select the best answer (10pts)

    (1). (2 pts) A bomb calorimeter ( the one I brought to class) measures ( )

    a. the work done by the system at constant volume. b. the work done by the system at constant pressure. c. the heat released by the system at constant volume. d. the heat released by the system at constant pressure.

(2). (2 pts) Which of the following is not one of the Laws of Thermodynamics. ( )

    a. The entropy at 0C is zero.

    b. For an isolated system a spontaneous process results in an increase of the entropy

    of the system.

c. The entropy of the universe increases.

    d. ;E = q +w

(3). (2 pts) If the first Law of Thermodynamics is stated as ;E = q - w, which of the

    following statements is true? ( )

    a. For w > 0, this represents work done by the system.

    b. For q >0, this represents heat released by the system. c. For w > 0, this represents work done on the system.

    d. None of the above.

(4). (2 pts) Which of the following is false with regards to a state function? ( )

    a. Changes in state functions only depend on the initial and final states. b. Enthalpy is a state function.

    c. Heat at constant pressure may be considered a state function d. Entropy is a state function

    e. Work is a state function.

    (5) (2 pts) There is a spontaneous process carrying out in a closed system: ( )

    -1-1a. ;S> 0 J.mol.K sys.

    -1-1b. ;S< 0 J.mol.K sys.

    -1-1c. ;S= 0 J.mol.K sys.

    d. None of the above.

    2 .Match the best description from the right column with the formula from the left column (there is only one best match) (10 pts)

    3. (15pts)Thermodynamics: As it was known thermodynamic data for all compounds at 298.15 K, 1 bar

    -1(1) (5pts) Determine ;H (298.15 K ) of the following reaction in kJ mol r

    (COOH) (s) + ? O(g) 2CO(g) + HO(l) 2222

    -1 (2) (5pts) Compute ;H (298.15 K ) kJ molfor reaction: r

    (COOH) (s) + H(g) 2 HCOOH (l) 22

    Based on the following reactions:

    (COOH)2 (s) + ? O(g) 2CO(g) + HO(l) 222

    HCOOH (l) + ? O(g) CO(g) + HO(l) 222

    H(g) + ? O(g) H2O(l) 22

    (3) (5pts) Using part b’s answer, determine the ;H in kJ for

     (COOH) (s) + H(g) 2 HCOOH (l) if 276.18 g of HCOOH (l) is produced. 22

4. (10pts) Thermodynamics: Thermal decomposition of calcium carbonate (calcite)

    proceeds according to the following reaction:

Calculate the pressure of CO at equilibrium with solid calcium carbonate and 2

    calcium oxide at 1500 K.

    -1-1( ;G (298.15K,CaCO): -1128.79 kJ mol; ;G (298.15K,CaO): -604.03kJ mol; f3f

    -1-1-1;G (298.15K,CO): -394.359kJ mol; ;C 0 kJ molK) f2P.

5. (15 pts) Chemical kinetics:

    (1) (5pts) Outline the assumptions made in the steady state approximation when

    applied to chemical rate laws. Your answer should make reference to the rates of

    the individual elementary reactions and the time dependence of reactant and

    product concentrations.

(2) (10pts) :

    Assuming that steady state conditions apply, show that the reaction obeys the following rate law:

6. (15 pts) Electrochemistry:

    (1) (5pts) What is meant by a standard electrode potential? Discuss the use of such quantities.

    pts) E(2) (10 for the cell Pt(s) H (g) HCl(aq) Hg Cl (s) Hg(l) is +0.2699 V at 222

    293 K and +0.2669 V at 303 K:

    (i) Write down the cell equation

    (ii) Calculate ;rS, ;rHand the equilibrium constant K at 298 K.

7. (15 pts) Surfaces:

    (1) (5pts) The principal features of chemisorption are expected to be well described by the Langmuir adsorption isotherm

    where P is the pressure of the gas and K is independent of pressure. Derive this equation, stating clearly the assumptions on which it is based. Why does the Langmuir isotherm fail to describe the characteristics of physisorption? (2) (10pts) Carbon monoxide is found to adsorb on the (111) surface of a particular transition metal single crystal. N, the number of CO molecules adsorbed per square metre, is measured as a function of CO gas pressure, PCO, at 400K. The results are

    presented in the table below:

    Show that the data conform to the Langmuir isotherm equation (1) above. Calculate the values for K and for N, the maximum surface concentration of CO

    which can be chemisorbed.

8. (10pts) Solutions:

    Two pure liquids A and B form an ideal solution when mixed together. (1) Describe how the partial vapour pressures of the two substances in the mixture will vary with changes in mixture composition and show their chemical potentials. (2) Calculate values for the Gibbs energy and entropy of mixing at 298 K when x = 0.75. B

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