Hgg A sample of (ideal) gas from a compressed gas cylinder goes from 230 atm to
ID: 787886 • Letter: H
Question
Hgg
A sample of (ideal) gas from a compressed gas cylinder goes from 230 atm to 1 atm, with a concurrent change of volume wherein 1 cm 3 expands to 230 cm 3 in volume. Assume that the temperature remains (or becomes) the same for the initial and final states. Calculate the change in entropy for 1 mole of the gas undergoing this process. Does your answer make sense? Why or why not? Determine the entropy of formation, Delta fS, of the following compounds. Assume 25 degree C. (a) H2O (l) (b) H2O (g) (c) Fe2(SO4)3 (d) Al2O3 (e) C (diamond)Explanation / Answer
1)
deltaS = 2.303nRlog(p1/p2)
= 2.303*1*2*log(1/230)
= - 11.008 cal
2)
deltaS = S(products) - S(reactents)
H2O(l) ...........> H2(l) + 1/2O2(l)
H2O(g)..................> H2(g) + 1/2O2(g)
Fe2(SO4)3................> 3Fe+2 + 2 SO4-3
C(diamond)..................> C(graphite)