Free energy 180-181

Question 1

Define the free energy change.

Answer 1

The free energy change is the balance between enthalpy, entropy and temperature for a process:

ΠG = ΠH - TΠS

A process can take place spontaneously when ΠG < 0

Question 2

Generally when will a process become spontaneous?(not in terms of the equation.)

Answer 2

A process is spontaneous if a chemical system becomes more stable and its overall energy decreases. The overall energy decrease results from contriutions from both enthalpy and entropy.

Question 3

What three factors determine if a process is spontaneous or not?

Answer 3

• The temperature, T, in Kelvin
• The entropy change in the system, ΠS.
• The enthalpy change, ΠH, with the surroundings.

Question 4

What must happen to the overall energy for a reaction to become feasible?

Answer 4

For a reaction to be feasile, there must be a decreases in the overall energy derived from both the enthalpy change and the entropy of the system.

Question 5

Draw a table with the columns:

ΠH, ΠS, ΠG, feasibility.

Do this for the possible combination of positive/negative values of ΠH and ΠS.

Answer 5