2.2 Thermal Properties & Temperature Flashcards
What is thermal expansion?
When a material is heated, the particles have more kinetic energy so move more, resulting in more space between molecules - and ultimately resulting in the material expanding.
Which state of matter experiences the most thermal expansion?
Gases, because the particles have most freedom to move.
Define specific thermal capacity
The amount of energy needed to raise the temperature of 1kg of a substance by
1°C.
Give the equation linking energy and specific heat capacity
E = mc🔼T
E = energy (J)
c = specific heat capacity (J/kg°C)
m = mass (kg)
🔼T = change in temperature (°C)
Define internal energy.
The energy stored by particles within a system.
What kind of energy are stored as internal energy?
Kinetic and potential.
How does heating affect internal energy?
It increases internal energy. The particles gain energy and move more, increasing their kinetic energy and therefore increasing the overall internal energy.
What does an increase in internal energy result in?
A change of state or an increase in temperature.
Describe how to calculate the thermal capacity of a material
• Use an electric heater to heat a substance for a set time
• Work out energy from E=Pt (from the power of the heater)
• Measure the temperature change with a thermometer
• Calculate specific heat capacity from E=mc🔼T
Define specific latent heat.
The amount of energy needed to change the state of 1kg of a substance without changing its temperature.
What are the 2 types of specific latent heat?
Specific latent heat of fusion - energy to change between solid and liquid (melt/freeze)
Specific latent heat of vaporisation - energy to change between liquid and gas (boil/condense)
Give the equation for energy for a change of state
E = mL
Energy (J) = mass (kg) x specific latent heat (J/kg)
Define melting point.
The temperature at which a material in solid form will become a liquid.
Define boiling point.
The temperature at which a material in liquid form will become a gas.
