Quiz | Chemical Thermodynamics

General Chemistry 3 - Quiz

1

Which of the following statements best describes the Second Law of Thermodynamics?

Second Law of Thermodynamics: the total entropy of an isolated system can never decrease over time and is constant if all processes are reversible ⇒ the entropy change is never negative: ΔSsystem + ΔSsurrounding ≥ 0

Law of Thermodynamics
2

What is the expression of the Gibbs energy change?

Gibbs Energy Change and Spontaneity of Reactions
3

Which of the following criteria for reaction spontaneity is incorrect?

ΔGrxn = RT ln QK

Gibbs criteria for reaction spontaneity:
If Q < K  ⇔  ΔGrxn < 0: reaction proceeds spontaneously from left to right
If Q > K  ⇔  ΔGrxn > 0: reaction proceeds spontaneously from right to left
If Q = K  ⇔  ΔGrxn = 0: reaction is at equilibrium

Gibbs Energy Change and Spontaneity of Reactions Gibbs Energy Change and Reaction Quotient
4

Which of the following statements is always true when a reversible chemical reaction has attained equilibrium?

Gibbs Energy Change and Spontaneity of Reactions Gibbs Energy Change and Reaction Quotient
5

What is the relationship between the equilibrium constant K and the temperature T?

ln K = - ∆H0rxnRT + ∆S0rxnR ⇒ a plot of ln K versus 1T is linear (ln K and 1T are proportional)

Van’t Hoff and Clapeyron-Clausius Equations
6

When does the entropy usually increase?

Entropy S is a measure of the amount of disorder in a system ⇒ the greater the disorder the higher the entropy.
The disorder of a system is greatest when a molecule is broken into 2 or more molecules or when a solid turns into a liquid or when a liquid turns into a gas

Law of Thermodynamics Entropy Changes for Reactions