AP Chem 9.1-9.11 Combo

Which room above has the least entropy?

• Room B

• Room A

• Room C

• Room D

The symbol for a change in entropy occurring in the diagram above ….

• +ΔH

• +ΔS

• -ΔG

• -ΔS

Fill in the blank: An increase in entropy (+ΔS) occurs when a solid becomes a ______. The molecules that compose a liquid are more random or disorganized than a solid.

• liquid

• gas

• plasma

• crystal

Which of the following changes is associated with an increase in entropy (+ΔS)?

• H2O(l) → H2O(s)

• Cl2(g) → Cl2(l)

• H2O(s) → H2O(l)

• N2(g) + 3H2(g) → 2NH3(g)

Consider the reaction: N2(g) + 3H2(g) ↔ 2NH3(g). What is the sign of the entropy change (ΔS) for this reaction?

• Positive

• Negative

• Zero

• Cannot be determined

The entropy of a system will increase if the temperature of a system increases. What happens to the entropy (ΔS) when the temperature increases?

• +ΔS

• -ΔS

• No change

• Cannot be determined

Fill in the blank: The more complex the molecule, the greater its entropy. Hexane (C6H14) has a greater entropy than propane (C3H8) because there are a greater number of ways they can move in ________ space.

• three dimensional

• two dimensional

• one dimensional

• four dimensional

A perfect crystal is said to have an entropy value of ________.

• zero

• infinity

• one

• hundred

Predict the signs for the changes in enthalpy ΔH and entropy ΔS when moving left to right on the boiling plateau.

• ΔH is positive, ΔS is positive

• ΔH is negative, ΔS is negative

• ΔH is positive, ΔS is negative

• ΔH is negative, ΔS is positive

Predict the sign of entropy change for the following. CO₂(g) + 2NH₃(g) → CO(NH₂)₂ (s) + H₂O(l)

• Negative; Entropy decreases because gases are converted to a solid and a liquid.

• Positive; Entropy increases because a solid and a liquid are converted to gases.

• Zero; There is no change in entropy as the number of molecules remains the same.

• Positive; Entropy increases because more products are formed than reactants.