As compared with separate gases, a mixture of gases is ____________

• more random.

• less random.

• equally random.

• less favorable.

The study of the transfers of energy that accompany chemical reactions and

physical changes is called (a)   .

Free-energy change depends on temperature, entropy change, and ​ (b)   change.


Free energy is measured in units called ​ (c)   .


The measure of the average kinetic energy of the particles in a sample of

matter is its ​ (d)   .


The energy transferred between samples of matter because of a difference in

their temperatures is called ​ (e)   .

• thermochemistry
• temperature
• heat
• enthalpy
• joules

A compound that is very unstable and likely to decompose violently

has an enthalpy of formation that is ______________

• small and negative.

• small and positive.

• large and negative.

• large and positive.

The specific heat of a substance is dependent on the energy lost or gained,

temperature, and ​ (a)   .

The enthalpy change is always the difference between the enthalpies of the

​ (b)   and the ​ (c)   .

As a general rule, when a substance goes from a liquid to a gas, the entropy

​ (d)   .

When the enthalpy of a reaction is negative and the entropy is positive, the

Gibbs free energy is always ​ (e)   .

• mass
• products
• reactants
• increases
• spontaneous

The ​ (a)   is negative for exothermic reactions and

positive for endothermic reactions.

• enthalpy change
• entropy change
• free energy
• none is correct

A reaction for which ΔH = -500 kJ is ______

• definitely spontaneous.

• probably spontaneous.

• probably nonspontaneous.

• definitely nonspontaneous.

Which of the following is not directly measurable?

• enthalpy of formation

• enthalpy of combustion

• enthalpy

• change in enthalpy

An endothermic reaction has

• a positive enthalpy change.

• a negative enthalpy change.

• no enthalpy change.

• either a positive or a negative enthalpy change.

Which of the equations below is an example of a thermochemical

equation?

• Mg(s) + 2H₃O⁺(aq) + Cl^-(aq) →

  Mg²⁺(aq) + 2Cl^-(aq) + H₂(g) + H₂O(l)

• Mg + 2H₃O⁺ + Cl^- → Mg²⁺ + 2Cl^- + H₂ + H₂O

• 2H₂(g) + 2O₂(g) → H₂O(g)

• 2H₂(g) + 2O₂(g) → H₂O(g) + 483.6 kJ

Match each description with the correct term.

• Exothermic

• Negative change in Gibbs free

  energy

• Endothermic

• Negative change in enthalpy

• Reaction that increases

  disorder

• Negative ΔS

• Spontaneous

• Positive ΔH

• Reaction that Decreases

  disorder

• Positive change in entropy