Topic 3: Particle Model of Matter Flashcards
What is internal energy?
The total energy stored inside a system by the particles that make up the system due to their motion and positions
What two stores do molecules within a substance have energy in?
- Kinetic
- Potential
How does heating change substance’s internal energy?
Increasing kinetic energy and store of particles
What does an increase in kinetic and internal energy do to a system?
- Temp. of system to increase
- Change of state
What happens to energy transfer when a substance reaches a certain temperature during heating?
Energy stops being transferred to the kinetic store of the molecules and is instead transferred to their potential store.
What does the energy transferred to the potential store do during a change of state?
It overcomes the intermolecular forces of attraction, causing the molecules to move further apart.
What happens to the potential energy of molecules during a change of state?
The potential energy increases, allowing the molecules to overcome intermolecular forces.
What happens to the kinetic energy and temperature during a change of state?
The kinetic energy remains the same, so the temperature stays constant even though heating continues.
Give an example of a change of state caused by energy transfer to the potential store.
A liquid changing to a gas (e.g., water boiling into steam).
What is the increase in temperature of a system dependent on?
- The mass of the substance heated
- The type of material
- The energy input to the system
What is the definition for the specific heat capacity of a substance?
The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C
What is the equation for specific heat capacity?
ΔE = mcΔθ
Where:
ΔE = change in energy, in joules (J)
m = mass, in kilograms (kg)
c = specific heat capacity, in joules per kilogram per degree Celsius (J/kg °C)
Δθ = change in temperature, in degrees Celsius (°C)
What does it mean for a substance to have a low specific heat capacity?
- Heats up and cools quickly
- Takes less energy to change its temperature
What does it mean for a substance to have high specific heat capacity?
- Heats up and cools slowly
- Takes more energy to change its temperature
What is specific heat capacity mainly used for?
Liquids and Solids
What does the specific heat capacity of different substances determine?
How useful they would be for a specific purpose e.g best material for kitchen appliance
What is the specific heat capacity of aluminium?
910 J/kg°C
What is the specific heat capacity of copper?
390 J/kg°C
What is the specific heat capacity of lead?
126 J/kg°C
What is the specific heat capacity of glass?
500-680 J/kg°C
What is the specific heat capacity of water?
4200 J/kg°C
What is the specific heat capacity of mercury?
140 J/kg°C
What is density?
Mass per unit volume of a material
What is the equation for density?
p = m/V
Where:
p = Density (kgm⁻³)
m = Mass (kg)
V = Volume (m³)