Ch. 16 (Energy and Chemical Change)

Which of these increases when the sign of 𝚫S is negative?

• Disorder

• Temperature

• Order

• Kinetic energy

Which of these would always be called a spontaneous reaction?

• A reaction with a –𝚫S and a +𝚫H

• A reaction with a –𝚫H and a –𝚫S

• A reaction with a +𝚫H and a +𝚫S

• A reaction with a +𝚫S and a –𝚫H

Which of the following substances has an enthalpy value of 0 at 298 K and 1 atmosphere of pressure?

• HCl(aq)

• Na(s)

• NaOH(s)

• CO₂(g)

Energy that is available to do work is ____.

• enthalpy

• entropy

• random molecular motion

• free energy

Fusion, or melting, is an endothermic process because it —

• requires heat to be transferred from system to surroundings and has a 𝚫H that is negative

• requires heat to be transferred from surroundings to system and has a 𝚫H that is positive

• involves a decrease in entropy

• involves a decrease in kinetic energy

What is the heat content of a system at constant pressure called?

• heat of reaction

• heat of the system

• enthalpy

• entropy

In thermochemistry, the specific part of the universe you are studying is called ____

• system

• area

• enthalpy

• surroundings

Which of these is required for a reaction to be called exothermic?

• The enthalpy of the reactants must be less than that of the products.

• The sign of the change in enthalpy for the reaction must be positive.

• The enthalpy of the products must be less than that of the reactants.

• Heat must flow from the surroundings into the system.

Spontaneous processes always result in:

• an increase in entropy

• a decrease in entropy

• a decrease in randomness

• an increase in enthalpy

In which example is the ΔH° positive?

• an ice cube melting

• condensation forming on cold glass of water

• molten lava cooling to form solid rock

• water vapor changing directly into frost on windows