Enthalpy, entropy, gibbs free energy

Question 1

IMPORTANT NOTE :

1aii)

Answer 1

CONVERT JKMOL-1 –> KJMOL-1 by dividiing by 1000

(Entropy change here has been divided by 1000 )

Question 2

Explain what would happen to the pressure as the system was allowed to reach equilibrium.

2x + 3z–> y

Answer 2

(Pressure) decreases AND fewer molecules/moles

Question 3

The chemist repeated the experiment at the same temperature with 1.00 mol SO2 and an excess of O2. The gas mixture was still compressed to a volume of 250 cm3. State and explain, in terms of Kc, how the equilibrium yield of SO3 would be different from the yield in the first experiment.

Answer 3

Kc Kc does not change (with pressure/ concentration) 

Comparison of conc terms with more O2 [O2]/concentration of oxygen is greater OR denominator/bottom of Kc expression is greater 

QWC: yield of SO3 linked to Kc (Yield of) SO3 is greater/increases AND numerator/top of Kc expression is greater/increases 

key points : mention , state obvious : mention how reactant in denominator increases in conc thus kc increases, and kc is linked to the yield of product

Question 5

Answer 5

water -> ice

entrop decreases due to less disorder/ ways of rearranging molecules

carbonate + acid

entropy increases since it produces co2 which is a gas

entropy decreases

3O2–>2O3

3 moles of gas forms 2 moles of gas

Question 6

The enthalpy and entropy changes of a reaction both have a negative sign. Discuss how the feasibility of this reaction will change as the temperature increases.

Answer 6

as temperature increases, T delta S would be more negative , thus gibbs free energy would increase , therefore feasibility decreases

Question 7

note

Answer 7

dont forget to include the UNITS when calculating rate constant !

Question 8

State and explain how the feasibility of this reaction will change with increasing temperature.(Entropy is negative)

Answer 8

and Gibbs free energy increase whislt t delta s becoems more negative