Question

3. The following figures represent distributions of two types of gas molecules between by an open tube. In which figure is the entropy of the system maximized? e. These are equal entropy systems 4. Indicate which of the following reactions results in a positive ASsys. a. Ba(NO3)2(aq) + Na S0,(aq) = BaSO,($) +2 NaNO3(aq) b. 4 Fe(s) +3 0 () S 2 Fe 0,($) c. 2 H (g) + O2(g) 5 2 H,O(g) d. Zn(s) + 2 HCl(aq) = ZnCl(aq) +H_(g) e. 2 Na(s) +C1,(g) = NaCl(s)

Answer 1

3. Entropy depends upon the randomness of the particles. As the distance between the particles increase, the entropy increases. So, for maximum entropy the particles of the same gas must be as far away from each other as possible.

So, the correct option is c.

4. If phase change in the reaction is solid to liquid or liquid to gas or solid to gas, then the entropy change is positive. If the phase change is liquid to solid or gas to liquid or gas to solid then the phase change is negative.

As you can see, in option d, we have only solid and aqueous phases in the reactant side but aqueous and gaseous phases on the product side. So, the phase change is solid to gas. So, the entropy change is positive. In all the other options, you can observe that the phase changes point to negative entropy change.