Chapter 11- Internal Energy, Absolute Zero And Change Of State Flashcards
Heat def
The transfer of energy as a result of the random interchange of energy between two bodies in thermal contact, resulting in energy flowing from hot to cold
Work def
The energy transfer produced by the action of a macroscopic force
Internal energy def
The sum of the kinetic energy and the bond potential energies of all the molecules in the system
U= KE+ PE
Ideal gases is when…
No intermolecular forces are at work so the bond potential energy is 0
First law of thermodynamics
The internal energy of a system can only change by exchanging energy with its surroundings, either by doing work or by heating
🔺W >0 when
Work is done on the system
🔺W< 0 when
Work is done by the system
First law of thermodynamics eq
🔺U = 🔺W + 🔺H
When 🔺H< 0
The system is cooled
When 🔺H > 0
Then the system is heated
If temperature doesn’t change then…. 🔺U
🔺U = 0
U= KE + PE
The KE is temperature dependent
Liquid to gas
Evaporation
Gas to solid
Deposition
Solid to liquid
Melting
Liquid to solid
Solidification
Solid to gas
Sublimation
Gas to liquid
Condensation
Latent heat def
The amount of energy released of required for a change of state to occur without a change in temperature
Specific latent heat of FUSION
Energy required per unit mass to change a SOLID to a LIQUID without a change in temperature
Specific latent heat of VAPORISATION
The energy per unit mass required to change the state of a LIQUID into a VAPOUR without a change in temperature
Energy equation for latent heat
E= m(mass) x L(specific latent heat)
Specific latent heat unit
Jkg^-1
A graph shape during a state change
Stays stationary (straight line above time axis) All work being done is being used to increase PE not KE
Absolute zero definition for an ideal gas
The temperature at which an ideal gas has zero volume
The temperature at which the particles of a system have zero kinetic energy
Gases differ with three characteristics
- volume
- temperature
- pressure
Absolute zero def
The lowest temperature that can theoretically exist and is given a temperature of 0 Kelvin
What is zero-point energy?
The energy at absolute zero
Due to quantum fluctuations
Which are irrespective to temperature
Since 🔺E is never zero, there will always be fluctuations in the energy value
