In: Chemistry
Calculate ΔS°(universe) for the decomposition of 1 mol of gaseous phosphine (PH3) to form white phosphorus and gaseous hydrogen at 25 °C.
PH3 (g) ---------------> P (white ) + 3 /2 H2 (g)
ΔS° system = ΔS° products - ΔS° reactants
= ( 164.4 + 3/2 * 223.1 ) - 210.2
= 288.85 J / K
ΔH° = (0 + 3/2 * 0 ) - 5.4
= -5.4 kJ / mole
T = 273 + 25 = 298 K
ΔS°surr = - ΔH° / T
= 5.4 x 1000 / 298
= 18.12 J / K
ΔSo universe = ΔS° system + ΔS°surr
= 288.85 + 18.12
= 307 J / K
ΔSo universe = 307 J / K