Energy
Energy
**Energy ** – the ability to do work or produce ______
**Potential energy** – energy due to _____________ of an object
**Kinetic energy** – the energy of motion
Energy
The SI unit for energy is the** ____________**
1 J = 1 Kgm^{2 } / s^{2}
Another unit of energy that you may be more familiar with is the calorie
**calorie ** – amount of energy required to raise _____________
1 cal = 4.18 J
1000 calories = 1 Kilocalorie = 1 Calorie
Energy Conversions
Convert 15,500 joules into Calories
Formulas – Kinetic Energy
Kinetic energy
KE = ____________
KE = kinetic energy (joules)
m = mass (must be in Kg)
V = velocity (must be in m/s)
Formulas – Potential Energy
Potential Energy
PE = __________
PE = Potential Energy (J)
m = mass (Kg)
g = gravitational constant = 9.8 m/s^{2}
h = height (m)
Formulas - Work
Work (w) –______________
Force (F) – a push or pull on an object
W = mgd = Fd = PE
Work and potential energy can be looked at in the same light
No distance __________________
Examples
A bowler lifts a 5.4 kg bowling ball 1.6m and then drops it to the ground.
How much work was required to raise the ball?
Examples
How much potential energy does that ball have at this height?
If the ball is dropped and we assume that all of the potential energy is turned into kinetic energy, at what velocity will the bowling ball hit the ground?
More examples
What is the kinetic energy of 1 atom of Ar moving at 650 m/s?
1st Law of Thermodynamics
1^{st} Law of Thermodynamics – energy is conserved
The **law of conservation of energy** states that in any chemical reaction or physical process, energy can be converted from one form to another, but it is neither ____________________
1st Law of Thermodynamics
Since energy can neither be gained nor lost, the change in E can be calculated using:
DE = E_{f } – E_{i}
In a chemical reaction i indicates __________ and f indicated ____________
DE
DE has 3 parts:
A # indicating the _____________
A sign (+/-) indicating the _____________-
A unit
Thermochemistry
**Thermochemistry** is the study of _______________that accompany chemical reactions and phase changes.
In thermochemistry, the __________ is the specific part of the universe that contains the reaction or process you wish to study.
Thermochemistry
Everything in the universe other than the system is considered the ________________
Therefore, the ____________ is defined as the system plus the surroundings.
Relating D E to heat & work
The system can exchange energy with its surroundings in 2 ways: _________________
DE =_______
DE = change in energy
q = heat
w = work
q & w
Don’t forget q & w must have signs
In order to get the sign you must look at the system as a box and the surroundings as everything else
q & w
Anything going INTO the box will be ___
Anything going OUT of the box will be ________
Examples
A system absorbs 140 J of heat from the surroundings and does 85 J of work on the surroundings. Calculate D E.
Endothermic & Exothermic
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