Particle Model of Matter Flashcards
State the different states of matter in order (least to most) of density of atoms
Gas, liquid, solid
Describe the particle arrangement of 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. They 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 undergoes a change of state?
Mass
How does a change of state differ from a chemical change?
In a change of state, the material can return to having its previous properties if the change is reversed
What is sublimation?
When a solid changes into a gas without passing through a liquid state
What is the opposite of evaporation?
Condensation, which is when a gas changes into a liquid state
What is evaporation?
When a liquid changes into a gas state
When water boils in an open pan, why does the mass of the pan of water appear to decrease?
Some of the vapour will evaporate and turn into water vapour. This will leave the pan meaning the mass of the pan will decrease. The mass of the whole system however remains constant
Explain the processes involved when a bathroom mirror mists up
Hot water evaporates to form water vapour
This water vapour lands on the cooler mirror
The vapour condenses and returns to liquid state on the mirror’s surface
What is the internal energy of a substance?
The energy stored by the particles
The sum of the total kinetic and potential energies that make up the system
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 the substance
What two things can heating a substance do?
Raise its temperature
Change the state of a substance
What three factors determine the temperature change of a system?
Mass of substance being heated
Type of material
Energy inputted into the system
State the equation used to calculate the temperature change when a substance is heated. State the units
Change in thermal energy (j) = mass (kg) x specific heat capacity (j/kg) x temperature change (celsius)
Define specific heat capacity
The amount of energy needed to increase the temperature of 1kg of a substance by 1 degrees celsius
Describe how the internal energy and temperature of a substance changes when a change of state occurs
The internal energy of the substance will be increased or decreased
The 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 for the energy required to change state. State the units
Energy to change state (J) = mass (kg) x specific latent heat (J/kg)
What is the specific latent heat of fusion?
The energy required to change 1kg of a substance from solid state to liquid state without a change in temperature
What is the specific latent heat or vapourisation?
The energy required to change 1kg of a substance from liquid state to gas state without a change in temperature
Describe the motion of molecules in a gas
They are in constant random motion
What factor affects the average kinetic energy of gas molecules?
The temperature of the substance
The higher the temperature, the higher the average kinetic energy of the molecules
What effect does increasing temperature have on the pressure of a gas when held at constant volume?
Pressure of the gas will increase as the temperature increases
Why does pressure increase as temperature increases?
Kinetic energy of molecules increases
Collisions of molecules become more frequent
Greater rate of change of momentum
Greater force and therefore pressure
If gas A is at a low pressure, and gas B is at high pressure, what can be said about the rate of collisions in each gas?
There are more collisions per second in gas B than in gas A
The rate of collisions is higher in gas B
Describe the force that the pressure of a gas exerts on the walls of its container
The net force acts at right angles to the container’s surface
The force increases as pressure increases
Explain how increasing the volume of a gas results in a decrease in pressure
Molecules become more spread out and so time between collisions increases
This reduces the rate of collisions
Rate of change of momentum increases, and so force exerted on container decreases, resulting in low pressure
What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature?
It is constant
pv = constant
What is the unit used for pressure?
Pascal (Pa)
What increases when you do work on a gas?
The internal energy of the gas
This can also lead to an increase of temperature
Why does the temperature of air inside a bike pump increase when it is pumped?
Work is done on a gas when it is compressed
Doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules
Temperature increases with an increase of average kinetic energy
