A21 T2 CCEA Enthalpy, Entropy and Free Energy

What is entropy a measure of?

• Energy

• Disorder

• Temperature

• Pressure

What must be true for a reaction to be feasible in terms of free energy change (ΔG)?

• ΔG must be greater than zero

• ΔG must be less than zero

• ΔG must be equal to zero

• ΔG must be positive

What is required when calculating ΔG and manipulating quantities in terms of the number of moles present?

• Conversion between units

• Conversion between temperatures

• Conversion between volumes

• Conversion between pressures

What does the balance between entropy change and enthalpy change determine?

• The speed of a reaction

• The feasibility of a reaction

• The temperature of a reaction

• The pressure of a reaction

When are processes spontaneous in terms of free energy change?

• When the free energy change is positive

• When the free energy change is zero

• When the free energy change is negative

• When the free energy change is constant

Which type of reaction takes in heat from the surroundings?

• Exothermic reactions

• Spontaneous reactions

• Endothermic reactions

• Feasible reactions

What is a feasible reaction?

• A reaction that requires external help

• A reaction that cannot take place spontaneously

• A reaction that can take place spontaneously without any external help

• A reaction that releases heat

What factor, besides energy change, determines the feasibility of a reaction?

• Temperature

• Pressure

• Entropy

• Volume

What happens to entropy when a solid changes state to a liquid or gas?

• A) Entropy decreases

• B) Entropy remains the same

• C) Entropy increases

• D) Entropy fluctuates

Which of the following reactions shows an increase in entropy due to the production of gas molecules?

• Ca(s) + 2HCl(aq) → CaCl₂(aq) + H₂(g)

• H₂O(l) → H₂O(s)

• NaCl(s) → Na⁺(aq) + Cl^-(aq)

• CO₂(g) → CO₂(s)