Thermo-Thermo-ChemistryChemistry

Time to bring on the heat!

Energy vs. TemperatureEnergy vs. Temperature

Energy: The capacity to do work.

Temperature: Temperature: A measure of A measure of the the AVERAGEAVERAGE kinetic kinetic energy of energy of particles in a particles in a sample of sample of matter.matter.

Temperature vs. HeatTemperature vs. Heat

Heat: The flow of energy due to a temperature difference

Heat transfer occurs from the hotter substance to the cooler substance

ConductionConduction• The transfer of energy as heat between particles

as they collide within a substance or between two objects in contact.

• EX: Soup warming on the stove; soup warms the bowl

ConvectionConvection• The transfer of energy by

the movement of fluids (gas or liquid) with different temperatures.

• EX: You crawl out of a smoky room because the hot smoky air rises and cool clean air sinks to the floor

RadiationRadiation• The transfer of energy by electromagnetic

waves• EX: infrared radiation, visible light, &

ultraviolet rays

Endothermic vs. ExothermicEndothermic vs. Exothermic

Endothermic: A process that ABSORBS energy.

Exothermic: A process that RELEASES energy.

Making Ice & Heat PacksMaking Ice & Heat Packs

Which salts would make a good ice pack or a good heat pack?

Calcium AcetateSodium ChlorideAmmonium NitrateAmmonium ChlorideCalcium Chloride

Make this table on the back of Make this table on the back of your note sheet!your note sheet!

Compound GetsWarmer

Gets Colder

NoChange

Calcium Acetate

Sodium Chloride

Ammonium Nitrate

Ammonium Chloride

Calcium Chloride

Heating Solid Heating Solid WaterWater

The Hot Plate is at a Constant

Temperature

Phase Change Diagram of Water

Phase Change Diagram of Water

Solid Ice Warming

Phase Change Diagram of Water

TransitionSolid/Liquid(Stays @ 0°C)

Phase Change Diagram of Water

Liquid WaterWarming

Phase Change Diagram of Water

TransitionLiquid/Gas (Steam)

(Stays @ 100°C)

Phase Change Diagram of Water

Gas Warming

James Joule’s Experiment

James Joule’s experiment involved the conversion of mechanical energy to heat (thermal) energy.

Look at all of the paddle surfaces!

They allow for a lot of

FRICTION between water

molecules!

Friction between

molecules generates

heat energy!

We can measure the temperature

increase.