Topic 14

Created by

Stylish squirrel 21

Cards (35)

Describe the structure of particles in a
gas
Particles in a gas have almost no forces
between them therefore they are completely
free to move, and move at high speeds in
random directions.
Explain the pressure of a gas in terms of the motion
of particles
The particles move in random directions. When
they collide with the walls of a container they
exert a force which acts at a right angle to the
container. This causes pressure.
State the equation used to calculate pressure. Give
appropriate units.
Pressure (Pa) = Force (N) / Area (m²)
P = F / A
What factor affects the average kinetic energy of gas
molecules?
● The temperature of the gas
● 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?
Gas pressure 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
each surface of the container
● 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 so rate of
collision decreases
● 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
How do you convert between degree celsius and
kelvin?
Degrees Celsius,℃ + 273 = Kelvin, K
What is absolute zero?
−273 °C
Particles have no kinetic energy and do
not move.
What equation can be used to calculate the
pressure/volume for a gas for which the mass is
fixed and temperature is constant?
P₁ × V₁ = P₂ × V₂
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 increases the average kinetic energy of the
molecules
● Temperature increases with an increase of
average kinetic energy
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)
What is meant by a state of matter?
A form in which matter can exist, based
on the particle arrangement in a
substance.
State the different states of matter in order (least to
most) of density of atoms.
● Least dense: Gas
● Liquid
● Most dense: Solid
Use kinetic theory to explain the
structure of liquids.
The particles have some kinetic energy.
They are free to move and can move
around in random directions at very slow
speeds.
Explain the movement of particles in a solid.
The particles vibrate around a fixed
position as they do not have enough
kinetic energy to move freely
Describe the structure of particles in a gas
Particles in a gas have almost no forces
between them therefore they are completely
free to move, and move at high speeds in
random directions.
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 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
What two things can heating a substance do?
Raise its temperature and 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
What is sublimation?
When a solid turns directly into a gas
What is the difference between physical changes
and chemical changes in substances?
Physical changes can be reversed.
Chemical changes cannot be easily
reversed.
How does heating cause a substance to change
state?
Heating matter gives particles more potential
energy. This energy is used to break the bonds of
attraction, leading to a change of state.
Why does heating increase the temperature of
substance?
It increases the amount of thermal energy in
that substance. It also gives the particles
more kinetic energy, meaning they move
faster and their temperature increases.
State the equation used to calculate the energy
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)
Define specific heat capacity
The amount of energy needed to
increase the temperature of 1kg of a
substance by 1°C.
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. Give appropriate units.
Energy (J) = Mass (kg) x Specific latent heat (J/kg)
E = mL