Thermal Physics Flashcards
What is internal energy?
Equal to the sum of all the kinetic energies and potential energies of all the particles in the body
How are the kinetic and potential energies of a body distributed in it?
randomly
How can the internal energy of a system be increased?
By doing work to transfer energy to it
By increasing the temperature of the system
What happens when to the internal energy when the state of a substance changes?
It’s internal energy changes as the potential of the system changes when the kinetic energy is kept constant
Why does water turn to steam when it boils?
When temperature increases more the 100, the energy gained is no longer used to increase the temperature but instead to break bonds between water molecules. Because kinetic energy remains constant, potential energy changes
What is the definition of specific heat capacity?
the amount of energy required to increase the temperature of 1kg of a substance by 1K without changing its state
What is the definition of specific latent heat?
The amount of energy required to change the state of 1kg of a material without changing its temperature
What is the specific latent heat of fusion?
The amount of energy required to change the state of 1kg of a material from a solid to a liquid without changing its temperature
What is the specific latent heat of vaporisation?
The amount of energy required to change the state of 1kg of a material from a liquid to a gas without changing its temperature
What is Boyle’s law?
When temperature is constant, Pressure and volume are inversely proportional
What is Charles’ law
When pressure is constant volume and temperature are directly proportional
What is the pressure law?
When volume is constant, pressure and temperature are directly proportional
How do you convert Celsius to kelvin?
+273
What happens at absolute 0?
Volume and pressure of a gas are constant
What is molar mass?
the mass of one mole of a substance
How is work done on a gas to change its volume?
Through the transfer of thermal energy
What does the area under a pressure/volume graph represent?
The work done
What is Brownian motion?
The random motion of larger particles in a fluid caused by collisions surrounding particles
How was Brownian motion observed?
by looking at smoke particles under a microscope
What did Brownian motion contribute to?
The evidence for the existence of atoms and molecules
What assumptions are made in the kinetic theory model?
- No intermolecular forces act on the molecules
- The duration of collisions is negligible in comparison to the time between collisions
- The motion of molecules is random
- They experience perfectly elastic collisions
- The motion of molecules follow newtons laws
- The molecules move in straight lines between collisions
What is an ideal gas?
A gas that follows all the laws perfectly and has no potential energy
What is the kinetic energy of the gas proportional to?
The temperature
Explain the reality of Boyle’s law?
Clue: temperature is constant
As the volume decreases the particles become closer together. This causes the rate of collisions to increase. An increase in the rate of collisions leads to an increased rate of change of momentum. Consequently there is a force on the container walls so the pressure increases
Explain the reality of Charles’ law?
Clue: pressure is constant
As the temperature increases the average kinetic energy of the particles increases. As pressure is constant the rate of change of momentum has to be constant . To achieve this the rate of collisions has to be constant but as they are travelling faster, they have to be more separated therefore an increase in volume.
Explain the reality of the pressure law?
Clue: volume is constant
As temperature increases the average kinetic energy of the particles has increased so they are moving faster and there is higher rate of collisions. Since the particles are moving faster and the rate of collisions is higher the rate of change of momentum is increased therefore there is a greater force on the container so the pressure has increased
What is the difference between the gas laws and the kinetic theory model?
Gas laws have evidence behind them whereas the kinetic theory model is from theories and assumptions
What is the first law of thermodynamics?
Energy can’t be created or destroyed
What is the zeroth law of thermal dynamics?
If two thermodynamic systems are both in thermal equilibrium with a third system they are also in equilibrium with eachother
