Which of the following are true statments ?

Question

a) For the reaction CO2(g) → CO2(s)
entropy increases


b) For the reaction NaCl(s) + H2O(l) → NaCl(aq)
entropy increases


c) Molecules Cl2(g) should have have greater
entropy per mole, than molecules of SO2(g)


d) If entropy decreases for a certain process, the entropy of the universe increases

Answer 1

Correct ans: B&D

A) when a reaction indergoes from gas to solid, the entropy must be decreased because there is lesser randomness

B) Solid dissolved into liquid to form aqueous solution increase the randomness of the matter

C) Hard to determine, but there is no sense that you can know it without doing any experiment

D) The randomness of the Universe is always increasing so it is true (Matter tends to have to greatest randomness which can be explained by Brownian motion but it is too hard for High School Chemistry)

Answer 2

Entropy is (roughly) a measurement of disorder. If entropy is increasing then disorder is increasing. Entropy increases for the following:

solid --> liquid or gas
liquid --> gas
solid --> aqueous (especially if it is an electrolyte)
fewer molecules --> more molecules

Some links below may help.