Section 1. Chemical Energy: Energy that matter possess because of its chemical makeup. Where...
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Transcript of Section 1. Chemical Energy: Energy that matter possess because of its chemical makeup. Where...
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