1. 2-1 What is Energy

2. CHEMICAL ENERGY
The energy that matter possesses because of its chemical makeup
Comps. have chem. energy bec. of the atoms they contain and the bonds that hold them together
CHEMICAL BOND – a mutual attraction betw. diff. atoms that binds the atoms together

3. KINETIC ENERGY Energy a moving object has bec. of its motion
Atoms & molecs. are in constant motion

4. POTENTIAL ENERGY energy an object has bec. of its position
position of atoms
When positions change, bonds are formed or broken & energy is absorbed or released
rxns. change positions of atoms and potential energy changes

5. All chemical & physical changes involve a change in energy.
freezing
evaporating
dissolving
explosion
burning

6. Exothermic Reactions
Any Reaction or change in which energy is released.
Most reactions
Products have lower energy than reactants
Ex – burning
Explosion
Hand warmers

7. Endothermic Reactions
Change in which energy is absorbed
May require constant energy input to sustain rxn
May feel colder as it absorbs energy from the surroundings
Products are higher in energy than reactants
Examples:
Ice packs
Electrolysis of water

8. ENERGY
the capacity to do work

9. LAW OF CONSERVATION OF ENERGY
in any chemical or physical process, energy is neither created nor destroyed
total amt. of energy in the universe is constant
energy just changes form

10. Energy can be transferred.

11. HEAT
the sum total of kinetic energy of the particles in a sample of matter
can be transferred due to a difference in temp.

12. SYSTEM
a specific portion of matter in a given region of space that has been selected for study during an experiment or observation.
complex or simple
everything outside system is surroundings

13. Heat transfer:
System to surrounding
Surroundings to system

14. TEMPERATURE
a measure of the average kinetic energy of the particles in a sample of matter.
heat flows from high temp. to low temp.

15. Thermometer measures temp.
matter expands as its temp. incr
Celsius scale.
0oC is freezing pt. of water
Kelvin scale
0K is absolute zero – lowest temp. theoretically possible
oC = K – 273
K = oC + 273

16. Diff. substs. incr. temp. diff. amt. with same amt of heat added
SPECIFIC HEAT CAPACITY (cp) – The amt. of heat energy required to raise the temp. of 1 gram of a subst. by 1K (or 1 Co)
expressed in J / g . K (or J / g . Co)
Joule (J) – SI unit of energy
Heat energy (q) = m c t

17. Matter and energy are closely related
Einstien – E = mc2
implies matter and energy are equivalent
can be changed into ea. other