P3- Particle Model of Matter Flashcards
What is density?
The measure of the compactness of a substance
Density=
mass(kg)/volume(m^3)
What is internal energy?
The energy stored by the particles that make up a system
Where is the energy in a system stored?
By its particles
What is the internal energy of a system?
The total energy that its particles have in their kinetic and potential energy stores
How do particles gain energy?
Through heating
What conserves mass?
A change in state
What is it called when a solid goes straight to a gas?
Sublimating
Is a change in state a physical or chemical change?
Physical
What does a change in state require?
Energy
What do bonds do when condensing or freezing?
Form, which releases energy
What happens when bonds form?
The internal energy energy goes down, but the temperature doesn’t
What is specific latent heat?
The amount of energy needed to change the state of 1 kg mass
What is the difference of specific latent heat when heating and cooling?
Cooling is the energy released
What is specific latent called when changing from a solid to liquid?
specific latent heat of fusion
What is specific latent called when changing from a liquid to a gas?
specific latent heat of vaporisation
Specific latent heat=
mass/energy
What is the unit for specific latent heat?
j/kg
What does the particle model help with?
Explains how temperature, pressure, volume and energy in kinetic stores are all related
What do colliding gas particles create?
Pressure
What leads to a net force and gas pressure
increase?
Faster particles and more frequent collisions
Are pressure and volume inversely proportional?
Yes
pV=
constant
Can change in pressure cause a change in volume?
Yes
What can a change in pressure cause?
- A change in volume
- A net outwards force at right angles in the surface of its container
Why can there sometimes be a force on the outside of a container?
Because of the pressure on the gas around it
What can doing work on gas do to its temperature?
Increase it
What is it called when you transfer energy by applying a force?
You do work
What doing work on a gas increase?
It’s internal energy
What is an example of mechanically ‘doing work’?
A bike pump
What is the definition of density? State
the relevant equation with units.
● The mass per unit volume of a material
● ⍴=m/v
● Density (kg/m³), Mass (kg), Volume (m³)
State the different states of matter in order (least to
most) of density of atoms.
● Least dense: Gas
● Liquid
● Most dense: 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. In a change of state, the material can
return to having its previous properties if
the change is reversed. 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 evaporation?
When a liquid changes into a gas state.
What is is the opposite of evaporation?
Condensation, which is when a gas
changes into a liquid state.
When water boils in an open pan, why
does the mass of the pan of water
appear to decrease?
Some of the water 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
2. Change the state of the substance
What three factors determine the
temperature change of a system?
- Mass of substance being heated
- Type of material (Specific heat
capacity) - Energy inputted into the system
State the equation used to calculate the
temperature change when a substance
is heated. Give appropriate units.
● ΔE = m c Δ𝛉
● Energy (J), Mass (kg), Specific Heat
Capacity (J/kg/°C), Temperature (°C)
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
State the equation for the energy
required to change state. Give
appropriate units.
● Energy to change state = mass x
specific latent heat
● Energy (J), Mass (kg), 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.
Describe the motionof 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 (at a constant volume)?
● Kinetic energy of molecules increases ● Collisions between molecules becomes 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 a high pressure, what can be said
about the rate of collisions in each gas?
● There are more collisions per second
in gas A than in gas B
● The rate of collisions is higher in A
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 of pressure.
● Molecules become more spread out and so time
between collisions increases
● This reduces the rate of collisions
● Rate of change of momentum decreases, and so
force exerted on container decreases, resulting in
a lower 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.
p V = 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
