Question

Given the equation, H2O(g) + C(s) --> H2(g) + CO(g). Assume the temp does not change during the reaction (delta H and delta S do not change during the reaction and C(s) is graphite). Using the appendix, calculate the delta G. Then determine the lowest possible temp at which the reaction will be spontaneous.  

Answer 1

The given equation is

The data for for each of the component at 298.15 K standard temperature is

	-241.8	0.189
	0	0.00574
	0	0.131
	-110.5	0.197

Hence, the standard free energy change for the reaction can be calculated as

From the data above,

Similarly.

Hence, at T = 298.15 K, assuming the enthalpies and entropies remain constant.

We know that a reaction is spontaneous if the free energy change .

For our given reaction, the critical temperature at which can be calculated as

Hence, above 235.33 K which makes  . Hence, the minimum temperature at which the reaction is spontaneous is 235.33 K

Note: the answer might vary slightly depending upon the number of significant figures you take for the values in appendix.