Thermal Physics (Module 19) Flashcards
What is the first law of thermodynamics?
The change of internal energy of the object = the total energy transfer due to work done and heating.
Define internal energy.
The Internal energy is the sum of the random distributions of the kinetic and potential energies of its molecules.
What does absolute zero mean?
Absolute zero is when the absolute temperature is 0 Kelvin (-273 C). This is the coldest possible temperature.
Define specific heat capacity.
It is the energy needed to raise the temperature of unit mass of the substance by 1K without changing it’s state.
How do you work out specific heat capacity?
Q = MC x (Change in temperature)
What is the inversion tube experiment?
This is one of the experiments that is used to find out specific heat capacity of a certain substance. It is used by inverting a tube multiple times and measuring the temperature initially and after a certain amount of turns. Then using the equation c = gLn/(Change in temperature) to work out the specific heat capacity.
Define latent heat.
Latent heat is when a substance is heated and changes state. (Between vapour, liquid and solid)
What is latent heat of fusion?
This is when a solid has heated at its melting point and its atoms vibrate so much that they break their bonds. This substance would therefore become a liquid.
What is latent heat of vaporisation?
This is when a liquid has heated at its boiling point and it atoms gain enough kinetic energy to overcome the bonds. This substance would therefore become a vapour.
What does sublimation mean?
This is when solids vaporise directly when heated.
What is the specific latent heat of fusion and vaporisation?
Fusion –> the required energy needed to change the state from a solid to a liquid.
Vaporisation –> The required energy needed to change the state from a liquid to vapour.
How do you work out specific latent heat?
Q = Ml (Energy = mass times specific latent heat)
