Question

which of the following has the largest entropy at 25.0C and 1 atm ? CH4 H2 O2 F2 N2

Answer 1

Entropy increase with the increase in number of atom in a gaseous molecules and also with the increase in molar mass entropy increses. Among the given molecules except CH4, all the other molecules have 2 atoms while methane has 5 atoms. So methane has the highest entropy in terms of atomic number of atoms. If we consider the molar mass O2 has highest molar mass among other but it has 2 atoms. Here molar mass predominates over number of atom and therefore highest entropy value will given by Oxygen (O2).

H₂ Na 2 O CHA No. of atom 2 2 2 2 5 Molar Mass 2 14 18 32 16 (9/mot) Entropy ↑ of No. of atom 4) Molar Mass