topic: energy do now: 1. take out hw and open up your notes from yesterday
TRANSCRIPT
All physical & chemical changes are accompanied by change in energy
The chemistry of energy changes is known as Thermochemistry!
Energy: Ability to do WorkThe SI unit for an energy
measurement is called the Joule (J)
EXAMPLE: 1 Joule = amount of energy required to lift a golf ball 1 meter
Other Energy Units: calorie, Calorie, BTU’s
1 calorie = 4.18 Joules
1 Calorie = 1000 calories = 1 kilocalorie
There are 2 types of energy (we are going to draw another chart – like the on we did for matter – in our notebook
(Not a complete list!)
Energy
Mechanical – large enough to see
Kinetic Potential
Non-mechanical – too small to see
Chemical Heat Light Electrical Nuclear
Kinetic Energy (KE) – makes things move
• KE = ½ x Mass x Velocity2 = ½ mV2
• KE depends on how heavy and how fast
Law of Conservation of Energy
• Energy is neither created nor destroyed in ordinary chemical or physical change
Energy before = Energy after
Energy can be converted from one form to another
- potential to kinetic - radiant to electric- electric to heat - chemical to kinetic- chemical to electrical
Energy of Universe is conserved
Universe
EnvironmentEnvironment
System
Energy
Energy can move between the system and the environment
Two ways to classify chemical reaction:
1. energy (heat) is given off = exothermic
2. energy (heat) is absorbed = endothermic
Exothermic – releases heat to environment
QUESTION: What happens to the temperature of the environment?
QUESTION: What happens to temperature of system?
a
Environment
System
Energy
EXO - energy leaves system (exits)
Temperature of environment
Temperature of system
Endothermic – heat is absorbed by the system
QUESTION: What happens to the temperature of the environment?
QUESTION: What happens to temperature of system?
Endo - Energy enters system (enter)
Environment
System
Energy
Temperature of environment
Temperature of system
• Note: Heat flows from hotter object to cooler object
• Example; Cold pack on leg: Heat flows from the leg to the cold pack!– Leg cools down; cold pack warms up