ME Thermodynamics and Kinetics of Materials

Question 1

The Gibbs free energy change (ΔG) for a reaction at constant temperature and pressure determines spontaneity. Which condition indicates a spontaneous process?

Accepted Answer

ΔG < 0

Answer

ΔG > 0

Answer

ΔG = 0

Answer

ΔH > 0

Question 2

According to the Gibbs phase rule, for a binary system at equilibrium, the number of degrees of freedom F is given by:

Accepted Answer

F = C - P + 2

Answer

F = C + P - 2

Answer

F = P - C + 2

Answer

F = C + P + 2

Question 3

Which thermodynamic quantity directly relates the chemical potential of a component to its activity in a solution?

Accepted Answer

μ = μ° + RT ln(a)

Answer

μ = μ° - RT ln(a)

Answer

μ = μ° + RT/a

Answer

μ = μ° × RT × a

Question 4

For an ideal solution of two metals, the enthalpy of mixing (ΔH_mix) is:

Accepted Answer

Zero

Answer

Always positive

Answer

Always negative

Answer

Equal to TΔS_mix

Question 5

The Clausius-Clapeyron equation describes the relationship between pressure and temperature along a phase boundary. For most metals, the solid-liquid boundary has a slope (dP/dT) that is:

Accepted Answer

Positive and very steep

Answer

Negative

Answer

Zero

Answer

Positive and shallow

Question 6

Which expression correctly defines the equilibrium constant K for a chemical reaction in terms of standard Gibbs free energy change ΔG°?

Accepted Answer

ΔG° = -RT ln K

Answer

ΔG° = RT ln K

Answer

ΔG° = -RT/ln K

Answer

ΔG° = RT/K

Question 7

In a regular solution model, the excess Gibbs free energy (G^E) compared to an ideal solution is attributed to:

Accepted Answer

Excess enthalpy of mixing only

Answer

Excess entropy of mixing only

Answer

Both excess enthalpy and excess entropy of mixing

Answer

Neither enthalpy nor entropy contributions