Chem 105: Exam 3

ΔEsystem= -ΔEsurroundings

the energy lost by our system is gained by the surroundings and energy gained by our system comes from the surroundings

energy decrease what would be the sign for Δ energy

negative

energy increases what would be the sign for Δ energy

positive

State function

only concerned with its current position not the path taken to get there

What are the two ways that energy can be transferred?

heat and work

Heat

random kinetic motion of atoms, ions and molecules

Work

concerted movement in a certain direction

How do molecules work?

changes in temperature and volume (think only when dealing with gasses)

Exothermic

energy releases from the system, causing the temperature in the surroundings to increase (energy negative)

Endothermic

system absorbs energy, causing the temperature in the surroundings to decrease (energy positive)

Endothermic will feel

cold

Exothermic will feel

hot

ΔH fusion

the amount of heat needed to melt one mole of substance

ΔH vaporization

the amount of energy needed to evaporate one mole of substance

ΔH sublimation

the amount of energy needed to sublime one mole of a substance (solid to a gas)