SULIT
1.
JIK102
(a). Benzene has a melting point of 5.53 oC and a boiling point of 80.09 oC
at atmospheric pressure. Its density is 0.8787 g cm-3 when liquid and
0.899 g cm-3 when solid. It has Tc = 289.01 oC, Pc = 48.34 atm, Tt = 5.52 oC
and Pt = 0.0473 atm. Sketch a phase diagram. Starting from a point at 200
K and 66.5 atm, trace the following path when:
(i).
T increased to 585 K while keeping P constant.
(ii). P decreased to 38.5 atm while keeping T constant.
(iii). T decreased to 278.6 K while keeping P constant.
(iv). P decreased to 0.0025 atm while keeping T constant.
Identify the starting and final phases of benzene.
[15 marks]
(b). A small cylinder of helium gas used with a volume of 2.30 L and a pressure
of 13800 kPa at 25 oC was used to fill balloons. Show the number of
balloons that can be filled when each of the balloons has a volume of 1.5 L
and a pressure of 1.25 atm at 25 oC.
[5 marks]
2.
(a). For the reaction of H2(g) + Br2(g)
2 HBr(g), the values of Kp and
ΔHo at 1000 K are 2.1 x 106 and -107.7 kJ, respectively.
(i).
Calculate the partial pressures of H2, Br2 and HBr at equilibrium when
0.974 mol of Br2 is added to a 1.00 L reaction vessel that contains
1.22 mol of H2 gas at 1000 K.
SULIT
JIK102
(ii). For the equilibrium in part (i)., each of the following changes will
increase the equilibrium partial pressure of HBr.
[A]. Adding 0.10 mol of H2
[B]. Adding 0.10 mol of Br2
[C]. Decreasing the temperature to 700 K
Choose the change that will cause the greatest increase in pressure
of HBr. Explain your choice.
[16 marks]
(b). The concentration of H3O+ ions in a sample juice is 2.5 x 10-3 M. Calculate
the concentration of OH- ions. Identify the acid-base properties of the
solution.
[4 marks]
SULIT
JIK102
APPENDIX
Table 1
Specific Heat Values of Some Common Substances
Substance
Specific Heat (Jg-1 oC-1)
Al(s)
0.900
Au(s)
0.129
C(graphite)
0.720
C(diamond)
0.502
Cu(s)
0.385
Fe(s)
0.444
Hg(l)
0.139
H2O(l)
4.184
C2H5OH(l) -ethanol
2.46
Avogadro’s number = 6.022 x 1023
SULIT
JIK102
Gas Constant, R in various units
R = 8.314 J K-1 mol-1
R = 8.314 Pa m3 K-1 mol-1
R = 8.314 x 10-2 L bar K-1 mol-1
R = 0.0821 atm L K-1 mol-1
R = 62.36 L Torr K-1 mol-1
R = 1.987 cal mol-1 k-1
Unit of Pressure and Conversion Factors
Unit of Pressure
Symbol
Numerical Value
Pascal
Pa
1 Nm-2 = 1 kgm-1s-2
Atmosphere
atm
1 atm = 101325 Pa
Bar
Bar
1 bar = 105 Pa
Torr or millimeters of Hg
Torr
1 Torr = 101325/760 =
133.32 Pa
1 Cal = 4.184 J
F = 96,485 C/mol
Cp = 4.19 Jg-1K-1
K= 1.38 x 10-23 J/K
Types of Work
Types of
Work
Variables
Equation for
Work
Conventional
Units
Volume
Expansion
Pressure (P), Volume (V)
w= -∫PexternaldV
Pam3 = J
Stretching
Tension (γ), length (l)
w= -∫γdl
Nm = J
SULIT
JIK102
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