Calcium oxide, CaO, is manufactured by decomposition of calcium carbonate, CaCO3
ID: 872560 • Letter: C
Question
Calcium oxide, CaO, is manufactured by decomposition of calcium carbonate, CaCO3, in a furnace at 500 K:
CaCO3(s)?CaO(s)+CO2(g)
The spontaneity of a reaction can be determined from the free energy change for the reaction, ?G?.
A reaction is spontaneous when the free energy change is less than zero.
A reaction is nonspontaneous when the free energy change is greater than zero.
A reaction is in equilibrium when the free energy change is equal to zero.
A:For the decomposition of calcium carbonate, consider the following thermodynamic data:
Calculate the temperature in kelvins above which this reaction is spontaneous.
T=?
B: Calculate the equilibrium constant for the following reaction at room temperature, 25 ?C:
CaCO3(s)?CaO(s)+CO2(g)
K= ?
?H?rxn 178.5kJ/mol ?S?rxn 161.0J/(mol?K)Explanation / Answer
delta Hrxn= 178KJ/mol deltaSrxn=161 J/mol-K
A reaction is spontaneous when the free energy change is less than zero.
delta G= -ve
delta G = delta H - T delta S= 178KJ/mol - T X.161KJ/mol-K= -ve
for above equation to be negative
178< Tx0.161
T> 178 /0.161
T>1105.6 K
B- Go= - RT ln K
Go= 178 - 298x.161=178-47.978=130.022KJ
130.2x10^3 = - 8.314 x298 x2.303 log K
log K=-130x10^3 /5705.85= - 22.78
K= 1.65x10^-23