For each of the following processes, indicate whether the signs of S and H are expected to be positive, negative, or about zero.
(a) An explosive is detonated in a sealed container and the container becomes hot.
(b) Some nitrogen gas and some oxygen gas held in separate containers are allowed to mix.
(c) 1 mol CH4(g) and 2 mol O2(g) is formed from 1 mol CO2(g) and 2 mol H2O(l).
(d) An unstable liquid decomposes generating a gas and liberating heat.
(e) Liquid is formed by compressing a refrigeration gas.