1. UNIT 3: ENERGY

2. Aim # 1- what is the relationship between energy and temperature?
What is Energy?
The ability to do work or produce heat
Forms of energy:
Light (radio waves, microwaves) , electrical, ,magnetic, chemical, mechanical, nuclear

3. Temperature Temperature is the average kinetic energy of a substance
Temperature measure how fast particles are moving
*** Not a form of heat, it is a measurement of heat****
Thermometers use two fixed points, the boiling point and freezing point of water
BP = 100 ⁰ C (373 K)
FP and MP = 0 ⁰ C (273 K)
(Absolute Zero is 0 Kelvin )

4. Aim # 2 how can we use temp scales to convert to different units?
K= ⁰C ***All motion stops at Absolute zero Try the temperature conversions in your note packet

5. Temperature and heat
The flow of energy due to temperature difference, heat will flow from higher temperature to lower temperature
Heat is the total kinetic energy of a substance (q)
q is the unit for the quantity of heat involved in a physical or chemical change
This heat comes from bonds breaking and new bonds formed in a chemical reaction “BARF”

6. Potential energy (PE) is the energy in position, stored energy
Aim # 3 how does energy aid in chemical reactions? Potential and Kinetic energy
Potential energy (PE) is the energy in position, stored energy
ball at the top of a hill, chemical bonds (attachments) between atoms of a substance

7. Kinetic energy (KE) is energy in motion
A certain amount of energy is required to START a chemical reaction- activation energy
Once started all chemical changes involve another energy change
Physical changes do NOT always involve energy change
Types of energy change are exothermic or endothermic

8. Exothermic- “exit” Energy is released, given off, “feels” hot
Chemical Change
Example: metal and an acid reaction
Physical Change
Water freezing

9. Energy is absorbed, taken in, put in Chemical Change- will feel “cold”
Endothermic – “IN”
Energy is absorbed, taken in, put in
Chemical Change- will feel “cold”
Ba (OH)2 + NH4Cl
Physical change- energy is put in
Boiling water

10. AIM # 4 – HOW DO WE CALCULATE SPECIFIC HEAT? Calculating heat
Units of heat
Calorie- amount of heat required to raise the temperature of 1 gram of water 1⁰ C
Joule – SI unit of heat
1 calorie = 4.18 Joules
Heat equation
Heat= mass x specific heat capacity x change in temperature
q= m c t
T= t f - ti

11. Specific heat
Specific heat capacity is the amount of heat required to raise the temperature of 1 gram of a substance 1 ⁰ C
For water C= 4.18 J/g ⁰ C
Example # 1 : How much heat is required to raise the temperature of grams of water from 10.0 ⁰ C to 40.0 ⁰ C

12. HEAT CALCULATION PRACTICE

13. HEAT CALCULATION PRACTICE

14. AIM # 3: How can we represent/calculate the energy associated with phase changes?
Reference Table has the equations! (Table T)

15. HEATING/COOLING CURVES
Time

16. HEAT OF FUSION
Amount of heat needed to melt a solid under normal conditions
Freezing requires same amount of heat as melting
Heat lost in freezing = heat gained in melting
Hf = 334 J/g
Table T for equation: q = mHf

17. HEAT OF VAPORIZATION
Amount of heat needed to convert a liquid to gas under normal conditions
Condensation requires same amount of heat as vaporization
Heat lost in condensing steam = heat gained in boiling water
Hv = 2,260 J/g
Table T for equation :q = mHv

18. Energy Changes Associated with Phase Changes – Heat Formulas
Heat of Fusion (q=mHf) : Clues to use this formula would be the following words- melting, freezing, solidification, crystallization, solid to liquid, liquid to solid (this value for water is located on Reference Table B)
Heat of Vaporization (q=mHv) : : Clues to use this formula would be the following words – evaporation, vaporization, condensation, liquid to gas, gas to liquid, steam (this value for water is located on Reference Table B)
Anytime there is a temperature change (a substance cooling or being heated) you would use the q=mcΔT
Where ΔT = Tfinal – Tinitial

19. Calorimetry
A calorimeter is used to measure the heat absorbed or released in a chemical process by measuring the temperature change of an insulated mass of water ch?v=EAgbknIDKNo