6.1 Endothermic and Exothermic Processes

If work is done by a system, is it exothermic or endothermic?

Exothermic

If work is done on a system, is it exothermic or endothermic?

Endothermic

If it is exothermic, does temperature increase or decrease?

Increase

If it is endothermic, does temperature increase or decrease?

Decrease

Is going from solid to gas exothermic or endothermic?

Endothermic

Is going from gas to solid exothermic or endothermic?

Exothermic

What is it called when solid changes into gas?

Sublimation

What is it called when gas changes into solid?

Deposition

Which state has the highest energy?

Gas state

What do temperature changes in a system indicate?

Energy changes

What can energy changes in a system be described as?

Endothermic and exothermic processes

Examples of energy changes in a system that can be described as endothermic and exothermic processes:

Heating or cooling of a substance, phase changes, chemical transformations

What happens to the energy of a system when a chemical reaction occurs?

Decreases, increases, or remains the same

If energy of the system decreases, is it exothermic or endothermic?

Exothermic

If energy of the system increases, is it exothermic or endothermic?

Endothermic

What happens to the energy lost by the reacting species (system) for exothermic reactions?

Gained by the surroundings

For exothermic reactions, how do surroundings gain energy?

By heat transfer from or work done by system

For endothermic reactions, how does the system gain energy from surroundings?

By heat transfer to or work done on the system

Is the formation of a solution an exothermic or endothermic process?

Either one of the two

Whether the formation of a solution is an exothermic or endothermic process depends on what?

Relative strengths of intermolecular/interparticle interactions before and after the dissolution process

When studying energy changes and the flow of heat, it is helpful to do what?

Differentiate between system and surroundings

What does a system represent?

The portion of the universe that we choose to focus on

What does the surroundings represent?

Everything else other than the system

The portion of the universe where attractive forces between particles are broken and/or formed:

System

Examples of experiments during which a change in temperature may be observed:

A solute being dissolved in a solvent, forming a solution, or a chemical reaction occurring, forming a new substance

If temperature changes are detected in experiments where a solute is dissolved in a solvent, forming a solution, or where a chemical reaction occurs, forming a new substance, it is related to what?

Energy changes in the system

What are energy changes associated with at the particle level?

Attractive forces between particles

Breaking attractive forces between particles is an endothermic/exothermic process

Endothermic

What happens to energy during an endothermic process?

Absorbed

Forming attractive forces between particles is an endothermic/exothermic process

Exothermic

What happens to energy in an exothermic process?

Released

If a temperature change occurs during the process of forming a solution or during a chemical reaction, it is important to understand what?

The direction of heat flow between the system and surroundings

Is the thermometer usually considered to be part of the surroundings/system?

Surroundings

How does temperature change during endothermic reaction?

Decreases

Why does temperature decrease during endothermic reaction?

Because heat flows from the surroundings into the system

Why does temperature increase during exothermic reaction?

Because heat flows from the system into the surroundings

What does adding a hot piece of metal to water at room temperature involve?

Difference in kinetic energy

Does adding hot piece of metal to water at room temperature involve breaking and forming attractive forces between particles?

No