3.2

Question 1

If the enthalpy and entropy change for a process have the [1] sign (both negative or both positive) the [2] of the free energy change for the process will depend on the [3] . At some temperature the process may be spontaneous (negative value of ΔG) and at other temperature the process may be non-spontaneous (positive value of ΔG). The temperature where it changes from one to the other is called the [4] .

Answer 1

__1__ same
__3__ temperature
__2__ sign
__4__ crossover temperature

Question 2

Enthalpy changes are usually presented for standard conditions (25 °C and 1 atm), so to work out what the value would be at a different temperature we need to use which law?

Answer 2

Kirchhoff’s Law.