Question

1) ΔS depends not merely on q but on ______ . Although there are many possible paths that could take a system from its initial to final state, there is always only one _____ isothermal path between two states. Thus, ΔS _____ _______ the path taken between states. Options: q rev, reversible,irreversible, has only one particular value, regardless of, can have different values, which depends on, q sys2)Which system has the greatest entropy?1 mol of H2(g) at STP1 mol of H2(g) at 100∘C 0.5 atm1 mol of H2O(s) at 0∘C1 mol of H2O(l) at 25∘C3)During _____ , the temperature _____ but the entropy change can be large as molecules _____ their degrees of freedom and motion. Options: a phase change, remains constant, increases, heating, raises, reaction, decrease, falls

Answer 1

Answer:

1) qrev/ reversible/ has only one particular value/ regardless of;

2) 1 mol of H₂(g) at 0ºC

3) a phase change/ remains constant/ increase

Explanation:

1) The change can occur in a reversible or an irreversible process. When the change is reversible, the system and the surroundings can be restored to their original state by exactly reversing the change. In an irreversible process, that is not possible.

The entropy variation (ΔS) is calculated only in the reversible process because, in the irreversible one, it's difficult to determine it. So, ΔS depends on qrev, which is the heat for the reversible process.

There is only one reversible isothermal path between two states, that's why it's easy to calculate ΔS for it.

The value of ΔS doesn't depend on the path, but only on the initial and the final states, so ΔS has only one particular value regardless of the path taken between states.

2) The entropy is the measure of the disorganization of a system, so when the molecules are more distant and vibrating, the entropy is higher (Sgas > Sliquid > Ssolid), and when the temperature increases, the entropy decreases (ΔS = qrev/T), so 1 mol of H₂(g) at 0ºC has the greatest entropy.

3) During a phase change, for a pure substance, the temperature remains constant, until all the substance changes for the other phase. The entropy is the measure of the disorganization of a system, so when the degrees of freedom and motion of the molecules increase, the system becomes more disorganized, so the entropy increases.