Section 1Section 1

Chemical Energy:

Energy that matter possess because of its chemical makeup.

Where does the energy come from? Movements of the atoms Energy from the force of attraction between

Hydrogen and Oxygen

Chemical Energy

Chemical bond:

Force of attraction between different atoms

This attraction binds the atoms together

Chemical Energy

Chemical Energy

Kinetic Energy Energy an object

possesses due to its motion

Atoms and molecules are in constant motion

There is even movement between the atoms in an ice crystal

Potential Energy Energy an object has

because of its position

Ex: Water Figure 2-3

When bonds are formed or broken

All physical and chemical changes involve a

change in energy Examples:

1. Wood burns Gives off heat

2. Solid to melt Energy has to be added to make it melt

Energy: the capacity to do some type of work such as move an object.

Changes in Energy

Law of conservation of energy:

In any physical or chemical change, energy can change form but the total amount of energy remains constant

Energy can be converted from kinetic to potential energy but it cannot be created or destroyed.

Energy

Heat:

Total of the kinetic energy of the particles in a sample of matter.

Heat is the most common way to transfer energy

Chemists keep track of energy transfers by defining the system

Energy

System:

All of the components that are being studied at a given time.

Everything outside of the system is the surroundings

Example: Heat pack Page 43

Heat can be transferred from the system (heat pack) to its surroundings (your hands) on a cold day.

Heat energy can also be transferred from the surroundings to the heat pack.

Energy

Reactions in which heat is transferred from the

surroundings into the system are _______________ reactions. Endothermic reactions

Therefore, energy is not really “absorbed” it is converted into chemical energy or some other form of energy.

Energy

Temperature:

Measure of the average kinetic energy of the random motion of particles in a substance.

Temperature indicates how hot or cold something is.

To increase the temperature of water, energy has to be transferred to the water

As the temperature of the water increases the water molecules move and increase their average kinetic energy

Energy transfer as Heat

Specific Heat Capacity:

Amount of heat energy required to raise the temperature of a 1 gram substance by 1 Kelvin

The SI unit for energy is joule

Specific heat capacity is J/g x K

Table 2-2 has specific heats for some elements

Specific Heat

E = mc2

E = energy M = mass C = the speed of light in a vacuum (2.998 x 108

m/s)

This equation shows that energy has a mass equivalent

Example on page 47

Mass & Energy

Page 47

Questions 7-10

Do them on your iPad and send them to my email address

Practice Questions