Thermal Physics Flashcards
What is the internal energy equal to
The sum of all the kinetic energies and potential energies of all its particles
How are all the kinetic energies and potential energies distributed in a body
Randomly distributed
What are the two ways you can increase the internal energy of a system
- do work on the system to transfer energy to it (e.g moving its particles/changing its shape)
- increase the temperature of the system
What happens to the internal energy as the state of the substance changes
The internal energy also changes
Why does the internal energy change when when the substance exchanges state
The potential energy of the system changes while the kinetic energy of the system is kept constant
How can we demonstrate that if a substance changes state the internal energy also changes
By measuring the temperature id water as it boils
- the temperature increases up until 100 degrees Celsius after which the energy gained through heating the water is no longer used to increase the temperature ( and therefore the kinetic energy) but instead is used to break bonds between water molecules so it can change state to water vapour and so the potential energy is increased
What equation can you use to measure the amount of energy required to change the temperature of a substance
Q = m x c x change in temp Q=energy required m=mass c=specific heat capacity
What is the definition of specific heat capacity
Is the amount of energy required to increase the temperature of 1kg of a substance by 1 degree Celsius/1k without changing state
What equation can be used to measure the amount of energy required to change the state of a substance
Q = m x l Q=energy required m=mass l=specific latent heat
What is the definition of specific latent heat
The amount if energy required to change the state of 1kg of material, without changing its temperature
What are the two types of specific latent heat
Specific latent heat of fusion ( when solid changes to liquid )
Specific latent heat of vaporisation ( when liquid changes to gas )
What do the gas laws describe
The experimental relationship between pressure volume and temperature for a fixed mass of gas
Are the laws based on a theory or from observation and experimental evidence
From observation and experimental evidence which means they are empirical in nature
What are the three laws
1 - Boyle’s law
2 - Charles’ law
3 - The pressure Law
What is Boyle’s and it’s equation
When temperature is a constant and pressure and volume are inversely proportional
PV = K
What is Charles’ law and its equation
When pressure is a constant, volume is directly proportional to absolute temperature
V/T = K
What is the pressure law and its equation
When volume is constant, pressure is directly proportional to absolute temperature
P/T = K
What temperature measured in when using the gas laws
Kelvin
What is the value of absolute zero
0K = -273°C
What happens to particles when they reach absolute zero and what happens to a gas
They have no kinetic energy and the volume and pressure of a gas are zero
What equation do you get when you combine all the laws of gas
PV/T = K
What dies K equal to in the equation PV/T = K and what is the rearranged equation
K = nR where n is the number of moles and R is the molar gas constant and the new equation is PV = nRT
What is the value of the molar gas constant
8.31
What is the value of 1 mole of a substance
6.02 x 10^23 atoms/molecules
