Phase Equilibrium and Physical Transformation of Pure and Mixtures_1

51

Standard enthalpies of fusion and vaporization at the transition temperature

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.6 Assuming no hydrogen bonding or 52
other specific molecular interactions are
present, what is the standard enthalpy of Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.
vaporization for a liquid with a normal
boiling point of 55.23 0C?

Ex.7 What is the normal boiling point for a 53
liquid with a standard enthalpy of
vaporization of 25 kJ mol-1? Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.
Assume there are no hydrogen bonding or
other specific molecular interactions in the
liquid.

Ex.8 54

1) 26 kJ mol-1, 2) 27 kJ mol-1, 3) 310 K

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.9 55

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 56

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 57

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.10 58

1) 50.05 0C, 2) 78.57 0C.

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.11 59

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 60

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 61

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.12 62

1) 349 K, 2) 422 K

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.13 63

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 64

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 65

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.14 66

1) 206.6 torr, 2) p2 = 0.1294 atm

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.15 67

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 68

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Ex.16 69

1) 17.1 kJ mol-1, 2) 40.3 kJ mol-1

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

70

Ex.17 Calculate the effect on the chemical potentials of liquid water and water
vapour of increasing the temperature from 100 0C to 101 0C. The
standard molar entropy of liquid water at 100 0C is 86.8 J K-1 mol-1 and
that of water vapour at the same temperature is 195.98 J K-1 mol-1.

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

Solution 71

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

72

Ex.18 Calculate the effect on the chemical potentials of ice and water of
increasing the pressure from 1.00 bar to 2.00 bar at 0 oC. The density of
ice is 0.917 g cm-3 and that of liquid water is 0.999 g cm-3 under these
conditions.

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

73

Solution

We interpret the numerical results as follows: the chemical potential of ice rises more sharply than that of water, so if they
are initially in equilibrium at 1 bar, then there will be a tendency for the ice to melt at 2 bar.

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

74

Ex.19 Calculate the effect of an increase in pressure of 1.00 bar on the
liquid and solid phases of carbon dioxide (of molar mass 44.0 g mol-1)
in equilibrium with densities 2.35 g cm-3 and 2.50 g cm-3, respectively.

(l) = +1.87 J mol-1,(s) = +1.76 J mol-1, solid forms

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

75

Ex.20 Calculate the effect of applied pressure on the vapour pressure of liquid
water. For water, which has density 0.997 g cm-3 at 25 0C and therefore
molar volume 18.1 cm3 mol-1, when the pressure is increased by 10 bar

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

solution 76

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

77

Ex.21 Calculate the effect of an increase in pressure of 100 bar on the vapour
pressure of benzene at 25 oC, which has density 0.879 g cm-3.

[Ans 43 per cent]

Peter Atkins et.al. Physical Chemistry, 6th ed. 2006.

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