Question

Predict the direction of the entropy in each reaction.
a. CaCO3(s)-> CaO(s) +CO2(g0
b. NH3(g)+HCl(g)->NH4Cl(s)
c. 2NaHCO3-> Na2CO3(s)+H20(g) +CO2
d. CaO(s)+CO2(g)-> CaCO3

Answer 1

The secret here is to visualize the randomness of the substances. Entropy increases as we go from solid to liquid to gas. Solids are orderly with atoms essentially locked into place, liquids less orderly and more degrees of freedom for the molecules, gases the molecules can go every which way.
a. CaCO3 is solid, CaO is solid BUT CO2 is a gas so entropy increases in going from left to right.
b. gases going to solid; entropy decreases from left to right.

Answer 2

Positive