The G at nonstandard conditions can be found using the equation G=G°+RTlnQ Refer

Question

The G at nonstandard conditions can be found using the equation

G=G°+RTlnQ

Referring to the same reaction

Fe2O3 (s) + 3C (graphite) --> 2 Fe (s) + 3CO (g)

a) show the formula setup for Q (how it depends on concentrations and/or pressures). It is conventional in thermodynamics to use pressure for gases and molarities for aqueous solutions. When set up that way, Q may be a "hybrid" of both pressures and molarities.

b)Calculate the value of G at T = 1000 K and the P of CO = .1 atm

c) calculate the value of G at T= 1000 K and the P of CO=10 atm

d) as we see now, formation of a gas at high pressure has different G from formation of the same gas at low pressure. Explain how the results of parts (b) and (c) make sense using "freedom of molecular motion".

Please explain, Thank you.

Explanation / Answer

Q = [CO]3 since rest of the elements are solids

K= Equilibrium constant = [CO]3

for CO= 0.1 atm, K= (0.1)3= 0.001, deltaG= -RTlnK= -8.314*1000*ln(0.001)= 57431 Joules/mole

for CO= 10 atm K= (10)3= 1000, deltaG= -8.314*1000* 1000 =-8314000 joules/mole

so the process is spontaneous at 10 atm

As pressrue is increased, the entropy decreased, entropy decreases and freedom of molecules is restricted.

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