Theme B - B.1 - Thermal energy transfers Flashcards
What are the properties of solids?
- fixed volume and do not flow
- particles are arranged in regular rows
- particles have little energy hence can only vibrate around fixed positions
- Strong intermolecular forces
What happens when solids are heated?
- Particles gain energy-> Move further apart-> weakens intermolecular forces(thermal expansion)
- Solids expand less as comapred to liquids and gases
What are the properties of liquids?
- flow and take the shape of the container
- fixed volume
- random particle arrangement
- intermolecular forces are weaker than solids but stronger than gas
- More expansion than solids but less expansion than gases
What are the properties of gases?
- flow and take the shape of the container
- volume changes based on pressure and temperature
- particles are far and arranged randomly
- high energy and random movement
- gases expand the most
What is internal energy?
Sum of potential energy and kinetic energy. Changing either of these can change internal energy.
Which state of matter has the highest internal energy?
Gases.
What is density defined as?
Mass per unit volume.
What is the relationship between temperature and pressure?
if temperature decreases, pressure decreases and if temperature increases, pressure increases
What is absolute zero?
The lowest temperature possible where the pressure and volume of a substance is equal to zero and the particles have zero kinetic energy.
What is the absolute temperature?
The temperature on the kelvin scale.
What is the relationship between kinetic energy and temperature?
As kinetic energy increases, the temperature increases.
What is the formula for average kinetic energy of molecules?
E=(3/2)KT where E is the average kinetic energy of the molecules, K is the boltzman constant and T is the absolute temperature.
What is specific heat capacity?
The amount of energy required to increase the temperature of 1kg of a substance by 1K. Or: the heat released by a substance when its temperature decreases by 1K.
What is phase change?
When a substances changes from one phase to the other(e.g solid->liquid)
During a phase change, all energy supplied is transferred to the _ energy of the particles and not _ energy.
potential, kinetic
During phase change, the temperature of the substance _ _.
remains constant
What is the specific latent heat of a substance?
The amount of energy required to change the phase of 1kg of a substance at constant temperature. For solid->liquid it is the specific latent heat of fusion. For liquid->gas it is the specific latent heat of vaporisation.
What is the formula for latent heat?
Q = ml where Q is thermal energy, m is latent heat and l is latent heat.
When does a thermal energy transfer occur?
When there is a difference in temeperature between two bodies.
How does thermal energy transfer?
From an area of higher temeperature to an area of lower temperature until thermal equilibrium is reached.
What is conduction?
The transfer of thermal energy between particles in direct contact.
In which state of matter does conduction occur best in?
Solids, as the particles are really close to each other.
Describe the process of thermal energy transfer in solids.
Thermal energy is supplied to one part of the solid and gets converted into kinetic energy and the particles vibrate more. Kinetic energy is transferred to neighboring particles through collision. When thermal equilibrium is reached net transfer is zero.
Why are metals the best conductors?
They have a sea of delocalised electrons which transfer the heat throughout the metal.
