Slides on Endothermic vs Exothermic Reactions

Review: Endothermic vs Exothermic Processes

Bromfield Honors Chemistry

Multiple Choice

Energy that transfers from one substance to another until the temperatures are equal is called...

• free energy

• temperature

• entropy

• heat

Multiple Choice

Which of the following describes the heat transfer when you hold an ice cube in your hand?

• from the cold ice cube to your warm hand

• the cold ice cube makes your hand cold

• from your warm hand to the cold ice cube

• no heat transfer occurs

Multiple Choice

A(n) _____ is a balanced chemical equation that includes the physical states of all reactants and products and the energy change that accompanies the reaction

• thermochemical equation

• enthalpy of combustion

• formation reaction

• molar enthalpy of vaporization

Multiple Choice

A hot marble is dropped into a container of cool water. Which of the following statements most accurately describes the molecular motion of molecules?

• Both the marble molecules and the water molecules will slow down until they eventually come to rest.

• The marble molecules will slow down while the water molecules speed up until they reach reach the same average kinetic energy.

• The marble molecules will speed up while the water molecules will slow down until they reach nearly identical speeds.

• Both the marble molecules and the water molecules will speed up until they reach nearly identical speeds.

Multiple Choice

If the enthalpy (ΔH) is negative the reaction is ____.

• endothermic

• exothermic

Multiple Choice

If ΔH is positive, heat would be shown on the _____ side of the thermochemical equation.

• reactant

• product

Multiple Choice

A positive ΔH means that:

• In order for the reaction to happen, heat must be added to the system.

  The process is exothermic

• In order for the reaction to happen, heat must be added to the system.

  The process is endothermic.

• When the reaction happens, heat is released to the surroundings. The process is exothermic

• When the reaction happens, heat is released to the surroundings. The process is endothermic

Multiple Choice

A negative ΔH means the reaction is:

• complete

• at equilibrium

• exothermic

• endothermic

If we "flip" a thermochemical equation (ie., write it backwards), the sign of ΔH changes

ex.

+ΔH: A + B + heat ⟶ C

-ΔH: C ⟶ A + B + heat

Multiple Choice

Is the following process exothermic or endothermic?

2 Al + 3CuCl₂ ⟶ 2AlCl₃ + 3 Cu + heat

• endothermic

• exothermic