15.2 Entropy & Spontaneity

	MgCO3	MgO
ΔHӨf / kJ mol-1	-1095.8	-601.7
ΔSӨ / J mol-1	65.7	26.9

 

Write an equation for the decomposition and use section 12 of the data booklet and the information given to determine the enthalpy change for the decomposition of magnesium carbonate.

[3]

Use section 12 of the data booklet and the information given to determine the standard entropy change for the decomposition of magnesium carbonate.

[2]

Using your answer to part a) to determine if the decomposition of magnesium carbonate is feasible at 280 ℃. 

[1]

Used in the production of polymers, methanol is manufactured in large quantities.

State the equation for the combustion of methanol. 

[1]

Comment on the entropy change of the reaction. 

[2]

Use section 12 of the data booklet to determine the enthalpy change, ΔH_r , for the production of methanol from carbon monoxide and hydrogen. 

[3]

Use your answer to part b) and section 12 of the data booklet to calculate the free energy change, ΔG , for the formation of methanol from carbon monoxide and hydrogen at 300 K. 

[3]

A student states that if the temperature is lowered for the formation of methanol, the reaction will become non-spontaneous. Comment on the student’s statement.

[4]

The Ostwald process to produce nitric acid involves the oxidation of ammonia. The equation is shown below:

The free energy change, ΔG^Θ , for the oxidation of ammonia at 298 K is -959 kJ mol^-1.
Use section 12 of the data booklet, to calculate the entropy change for the oxidation of ammonia in J K^-1 mol^-1.

[3]

Use your answer to part a) and section 12 of the data booklet to determine the standard entropy of nitric oxide gas. 

[3]

Using section 1 and 2 in the data booklet determine the value for the free energy change, ΔG^Θ , in kJ mol^-1 for the reaction in part c).

[2]