Calculate the standard reaction entropy at 298 K of the following reactions.
(a) 2 CH3CHO(g) + O2(g) → 2 CH3COOH(l)
(b) 2 AgCl(s) + Br2(l) → 2 AgBr(s) + Cl2(g)
(c) Hg(l) + Cl2(g) → HgCl2(s)
For a) I get -386.1 J K−1 mol−1 which is correct. For b) and c) I get 93 J K−1 mol−1 and -155 J K−1 mol−1 respectively both of which are wrong.