P3 - Particle Model of Matter Flashcards
What is the definition of density?
The mass per unit of volume of a material.
What is the equation for density?
density = mass / volume
Describe the particle arrangement in a solid.
Tightly packed in a regular arrangement particles can only vibrate on the spot.
Describe the particle arrangement of a liquid.
Close together but with an irregular arrangement. Particles can flow over each other.
Describe the particle arrangement of a gas.
Separated with no regular arrangement. Particles can move freely.
What is always conserved when a substance changes state?
Mass
How does a change of state differ from a chemical change?
In a change of state, a substance can return to having it’s previous properties if the change is reversed.
What is sublimation?
When a solid turns into a gas without passing through the liquid state.
What is the internal energy of a substance?
The energy stored by the particles.
The total kinetic energy and potential energy of the particles.
How does heating affect the energy of a substance?
Heating transfers energy to the substance.
It increases the energy of the particles that make up that substance.
What two things can heating a substance do?
Raise the temperature.
Change the state.
What three factors determine the temperature change of a system?
Mass.
Specific Heat Capacity.
Energy transferred to the system.
How do you calculate temperature change when a substance is heated?
Temperature change = mass x SHC x inputted energy
Define Specific Heat Capacity.
The amount of energy needed to increase the temperature of 1kg of a substance by 1 degree.
How will the internal energy and temperature of a substance changes when a change of state occurs?
Internal energy will increase or decrease depending.
Temperature of the substance will remain constant.
Define Specific Latent Heat.
The amount of energy needed to change the state of 1kg of a substance with no change in temperature.
State the equation to calculate the energy required to change state.
Energy to change state = mass x SLH
What is the SLH of fusion?
The amount of energy require to change 1kg of a substance from solid state to liquid state without a change in temperature.
What is the SLH of vaporisation?
The amount of energy require to change 1kg of a substance from liquid state to gas state (vapor) without a change in temperature.
What factor affects the average kinetic energy of gas molecules?
The temperature of the substance.
Higher the temperature, higher the average kinetic energy of the gas molecules.
Why does pressure increase as temperature increases?
Kinetic energy of the molecules increases.
Leading to more collisions.
More changes of momentum.
Greater force and therefore, pressure.
Explain how an increase in the volume of a gas results in a decrease in pressure.
Molecules become more spread out so time between collisions increases.
Reduces rate of collisions.
Rate of change of momentum decreases so force exerted on walls decreases, leading to a decrease in pressure.
What is the unit used for pressure?
Pascal (Pa)
What increases when you do work on a gas?
Internal energy. Can then also lead to a temperature change.
Why does the temperature change inside a bike pump when it is being pumped?
Work is done on a gas when it is compressed.
This increases the thermal energy of the gas meaning the average kinetic energy of the molecules also, increases.
Temperature increases with an increase in kinetic energy.
Why in a heating graph does the temperature remain constant when a change of state occurs?
Because the energy is being used to break or weaken the forces of attraction between the particles instead of increasing temperature.
What is pressure?
Total force per unit of area.
