AP CHEM Unit 5 Day 1 Review

Front

What is molar entropy?

Back

Molar entropy is a measure of the amount of disorder or randomness in a system per mole of substance. It is typically expressed in units of J/(mol·K).

Front

List the substances in increasing order of their molar entropy: C(s), H2O(s), H2O(ℓ), H2O(g).

Back

C(s) < H2O(s) < H2O(ℓ) < H2O(g) - This order reflects the increasing disorder from solid to gas.

Front

What is the standard free-energy change (ΔG°) for a reaction?

Back

The standard free-energy change (ΔG°) is the change in free energy when reactants in their standard states are converted to products in their standard states at a specified temperature, usually 298 K.

Front

Calculate the standard free-energy change for the oxidation of magnetite to hematite at 298K.

Back

ΔG° = -196 kJ/mol_rxn.

Front

What does a negative ΔG° indicate about a reaction?

Back

A negative ΔG° indicates that the reaction is spontaneous under standard conditions.

Front

What is the change in entropy (ΔS) for the process H2O(g) → H2O(ℓ) at 1 atm and 100°C?

Back

The change in entropy (ΔS) is negative, indicating a decrease in disorder as gas condenses to liquid.

Front

What happens to cell voltage (E_cell) when the concentration of Cr(NO3)3 is decreased from 1.0M to 0.1M?

Back

E_cell decreases because the reaction quotient (Q) becomes greater than 1, shifting the equilibrium to the left.

Front

What is the relationship between total energy and total entropy in a sealed, insulated container when an ionic solid dissolves in water?

Back

Total Energy: Remains Constant; Entropy: Increases - The dissolution process increases the disorder of the system.

Front

Define entropy in the context of thermodynamics.

Back

Entropy is a measure of the dispersal of energy in a system and the degree of disorder or randomness in the arrangement of particles.

Front

What is the significance of the second law of thermodynamics?

Back

The second law states that the total entropy of an isolated system can never decrease over time, indicating that natural processes tend to move towards a state of greater disorder.