Tutorial 2
Chemistry 2402 – Thermodynamics – Toby Hudson & Peter Harrowell
1. Provide a brief explanation (no more than 4 lines) of each of the following terms.
(You may use an equation where appropriate.)
i) a heat engine
ii) chemical potential
iii) temperature
iv) pressure
v) Gibbs free energy
2) Water ice melts at 0 °C at 1 atm, with an enthalpy change of 6.0095 kJmol-1. The
volume decrease on melting is 1.65×10-6 m3mol-1. What change in the bulk melting
temperature will be observed if an ice skater increases the pressure by 12.0 atm? Is
this effect enough to explain the melting of ice while skating?
3) Napthalene melts at 353K at 1 atm with an enthalpy change of 19 kJmol -1. The
volume increase on melting is 19×10-6m3/mol. What change in the melting
temperature will be observed if the pressure is raised by 100 atm? (1 atm = 105 Nm-2.)
4) Under standard laboratory conditions, the melting point of iron is 1811 K. The
inner core of the earth is primarily composed of iron. It is solid, despite the core
being at a fairly uniform temperature of around 5600 K.
i) Give a brief explanation of how this is possible.
ii) Calculate an estimate of the pressure at the surface of the inner core, which is the
boundary between liquid iron and solid iron. You can assume that the volume
increase upon melting, 0.055 cm3mol−1, and the enthalpy of fusion, 13.8 kJmol-1,
remain constant.
Data
1 mmHg = 1.316 × 10-3 atm
1 atm = 1.013 × 105 pascal (1 pascal = 1 Nm-2)
0C = 273.15 K
i(soln) = io(liq) + kBTln(xi) for an ideal solution
dP
H

Clapeyron Equation (differential form)
dT TV
H  T2 
P2  P1 
ln   Clapeyron Equation (integrated form)
V  T1 
 ln K P
T
P
H o

RT 2
van't Hoff's equation (differential form)
 K P (T2 ) 
H o
  
ln 
R
 K P (T1 ) 
Boltzmann constant
Avogadro’s constant
Gas constant
1 1
   van't Hoff's equation (integrated form)
 T2 T1 
kB = 1.381 × 10-23 JK-1
NA = 6.023 × 1023 mol-1
R = kB × NA