BJU Chemistry Chapter 15

The heat that produces a phase change is called ________ heat.

• sensible

• latent

• entropic

• Enthalpic

Ammonia has a molar enthalpy of vaporization of 23.3 J/mol. Water's enthalpy of vaporization is 40.7 kJ/mol. What can we deduce from these figures?

• There are stronger intermolecular attractions between water molecules than between ammonia molecules.

• There are stronger intermolecular attractions between ammonia molecules than between water molecules.

• We can deduce nothing about intermolecular attractions from these figures.

• Water must have a higher entropy.

Tags

NGSS.HS-PS1-3

Why does hot water cool more slowly than metal?

• The metal has more entropy than water.

• Water has a higher specific heat than the metal.

• The metal has more enthalpy than water.

• Water has more enthalpy than the metal.

The specific heat of copper is 0.39 J/(g · °C), and that of silver is 0.23 J/(g·°C). Which metal would have the higher temperature if the same amount of thermal energy were added to 50.0 g of each metal?

• copper

• silver

Tags

NGSS.HS-PS3-1

In an endothermic reaction, how does the enthalpy of the reactants compare with the enthalpy of the products?

• The reactants have more enthalpy.

• The reactants have less enthalpy.

• There is no change in enthalpy.

• The enthalpy fluctuates.

In thermodynamics, standard state is defined as ___ °C and 1 atm of pressure.

• 0

• 1

• 25

• 100

A reaction that has a +ΔS has a(n) ________.

• increase in entropy

• decrease in entropy

An exothermic reaction involves breaking:

• weak bonds to form weak bonds.

• weaker bonds to form stronger bonds.

• strong bonds to form strong bonds

• stronger bonds to form weaker bonds.

Tags

NGSS.HS-PS1-4

A reaction in which both ΔH and ΔS are negative is:

• favorable at all temperatures

• unfavorable at high temperatures

• unfavorable at all temperatures

• favorable at low temperatures

Which of the following is the most thermodynamically favorable?

• negative enthalpy and negative entropy

• negative enthalpy and positive entropy

• positive enthalpy and negative entropy

• positive enthalpy and positive entropy