EnergyEverything that is not matter.

What Is Energy?Think of all the ways this word is used…

o.0?

Energy is the capacity to do work.◦ In chemistry, energy is most commonly used to do the

work necessary to change the temperature of a substance.

Temperature is a measure of the average kinetic energy of the particles that make up a substance.

All matter is made of atoms which are constantly in motion. The higher the temperature of a substance, the more energy

its particles have, and the faster they move. What happens when particles of higher energy

(higher temperature) bump into particles of lower energy (lower temperature)?

Energy

When two substances have different temperatures, energy flows between them.◦ We call this energy heat.◦ Heat ALWAYS flows from hot to cold.

The new temperature will be the average of the two original temperatures:

Tave = ½(T1 + T2)

Chemistry often involves the transfer of heat.◦ When a process results in the evolution of heat, it is said to be

exothermic.◦ When a process results in the absorption of heat, it is said to

be endothermic.

Heat

Can Energy Be Measured?

How?

Units of Heat Energy are calories.◦ Just like units of length are meters.

A calorie is the amount of heat energy required to raise 1 g of water by 1°C.◦ The calorie is a metric unit of measure.◦ The abbreviation is cal

The SI unit of heat energy is the joule.◦ The abbreviation is J

The equivalency statement between joules and calories is: 1cal = 4.184 J exactly◦ This can be used as a conversion factor between

the two units.

Calories

The Specific Heat Capacity of Matter

Does all matter hold the same amount of heat?

The Specific Heat Capacity of a substance is the amount of energy required to raise the temperature of one gram of that substance 1°C.◦ Specific Heat Capacity is a physical property.◦ Every substance has its own unique specific heat

capacity.

Some stuff heats up easily, and has a low value for specific heat capacity, like gold.

Some stuff takes a lot of energy to heat up, so it has a high value for specific heat capacity, like water.◦ Why is it good that the specific heat capacity of water is

so high?

Specific Heat Capacity

Q = Energy or heat required m = mass of the sample C = specific heat capacity ΔT = the change in temperature

◦ ΔT = Tf-Ti = final temp – initial temp

This equation can be used to find any of the variables above as long as the rest are known.

Calculations involving specific heat capacity: Q = mcΔT