Chemistry 340 Physical Chemistry for Biochemists
1. One mole of nitrogen is allowed to expand from 0.5 to 10 L. Calculate the change in
entropy using the ideal gas law.
2. (a) Integrate the Gibbs-Helmholtz equation to obtain an expression for ∆G2 at
temperature T2 in terms of ∆G1 at 1 T , assuming ∆H is independent of temperature.
(b) Obtain an expression for ∆G2 using the more accurate approximation that
∆ =∆ + − ∆ H H TT C 1 1 ( ) P where T1 is an arbitrary reference temperature.
3. When a liquid is compressed its Gibbs energy is increased. To a first approximation the
increase in molar Gibbs energy can be calculated using (/) , GP V T ∂∂ = assuming a
constant molar volume. What is the change in the molar Gibbs energy for liquid water
when it is compressed to 1000 bar?
4. An ideal gas is allowed to expand reversibly and isothermally (25 °C) from a pressure of
1 bar to a pressure of 0.1 bar. (a) What is the change in molar Gibbs energy? (b) What
would be the change in molar Gibbs energy if the process occurred irreversibly?
5. Helium is compressed isothermally and reversibly at 100 °C from a pressure of 2 to 10
bar. Calculate (a) q per mole, (b) w per mole, (c) ∆G, (d) ∆A, (e) ∆H, (f) ∆U, and (g)
∆S , assuming helium is an ideal gas.
6. Toluene is vaporized at its boiling point, 111 °C. The heat of vaporization at this
temperature is 1 361.9J g . − For the vaporization of toluene, calculate (a) w per mole, (b)
q per mole, (c) ∆H, (d) ∆U, (e) ∆G, and (f) ∆S.
