Unit 2B: Energy · 2019-10-10 · Energy of Phase Changes 2019.notebook 5 October 10, 2019 Oct...
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Energy of Phase Changes 2019.notebook 1 October 10, 2019 DO NOW 1. Name the two forms of energy. 2. What is temperature a measure of? https://www.youtube.com/watch?v=dmcevC55K3s Oct 61:47 PM Unit 2B: Energy Aim: To discuss the two main forms of energy and their interactions in nature
Transcript of Unit 2B: Energy · 2019-10-10 · Energy of Phase Changes 2019.notebook 5 October 10, 2019 Oct...
Energy of Phase Changes 2019.notebook
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October 10, 2019
DO NOW
1. Name the two forms of energy.
2. What is temperature a measure of?
https://www.youtube.com/watch?v=dmcevC55K3s
Oct 61:47 PM
Unit 2B: Energy
Aim: To discuss the two main forms of energy and their interactions in nature
Energy of Phase Changes 2019.notebook
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Energy: The ability to produce heat or do work.‐All objects have energy.
• Law of Conservation of Energy: ENERGY CANNOT BE CREATED OR DESTROYED BUT IS CONSERVED.
Energy is transferable.
Energy once used or transferred can become a class of energy that belongs to either KE or PE.
Classes of energy: Chemical, nuclear, thermal (heat), electrical, electromagnetic, mechanical
Energy of Phase Changes 2019.notebook
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Fire feels "hot" Ice feels "cold"
The fire is losing energy The ice is absorbing energy to the hand from the hand
Hand HandFire Ice
surroundings surroundingssystem system
Exothermic change: Heat is lost by the system to the surroundings
Endothermic change: Heat is absorbed by the system from the surroundings
CH4 + 2 O2 > CO2 + 2 H2O + 890.4 kJ 2 HI + 52 kJ > H2 + I2
Energy exits as a product.Energy is released as a product.
Energy enters as a reactant.Energy is absorbed with the reactants.
Reactants ProductsProductsReactants
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CH4 + 2 O2 > CO2 + H2O + 890.4 kJ 2 HI + 52 kJ > H2 + I2
Energy exits as a product.Energy is released as a product.
Energy enters as a reactant.Energy is absorbed with the reactants.
Exothermic Endothermic
Heat – the transfer of thermal energy due to a difference in temperature.
Energy will ALWAYS flow from a higher temperature to lower temperature until thermal equilibrium is reached.
(equal temperature)
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Oct 61:47 PM
Phase Changes and Energy
Aim: To examine the behavior of particles and energy during phase changes.
Nov 65:51 PM
Phase Changes
Temperature remains constant BECAUSE kinetic energy stays constant. The particle speed stays the same.
The energy that is changing and is responsible for the phase change is potential energy.
Phase changes occur at constant temperature.
mp/fp bp/cpex: H2O 0°C 100°C
melting point temperatures boiling point remain constant
the entire time
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Endothermic Phase Changes PE increases, KE stays constant.
Melting(fusion): s to l
Boiling(vaporization): l to g Condensation: g to l
Freezing(solidification): l to s
Sublimation: s to g Deposition: g to s
Heat absorbed causes the molecules to move apart by overcoming the intermolecular forces of attraction.
Heat released allows molecules to move back together and the intermolecular forces of attraction become stronger again.
Exothermic Phase Changes PE decreases, KE stays constant.
Oct 1611:27 AM
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Nov 168:29 AM
