Particle Model of Matter Flashcards
Changes of state
How is a physical change different to a chemcial change?
A physical change does not involve a change in the chemical structure, only in its physical properties
Density of materials
What is density?
Density is a way of saying how closely packed together the particles are in something. It is measured in kg/m^3
Density of materials
How do we know the level of uncertainity?
+/- half of the smallest measurement
Density of materials
Method to find the density of a regular object.
- measure the mass using a balance
- using a ruler/vernier callipers, measure the base, width and height
- volume = base x width x height
- density = mass / volume
Density of materials
Method to find the density of a small irregular object.
- measure the mass using a balance
- fill a measuring cylinder with any amount of water and record how much
- slowly submerge the object in and record the new volume
- new volume - old volume = volume of object
- density = mass / volume
Density of materials
Method to find the density of a large irregular object.
- Measure the mass with a balance
- Fill a eureka can with water level to the spout and place a beaker under it
- Slowly submerge the object in
- Measure the displaced water in a measuring cylinder to find the volume
- density = mass / volume
Internal energy
What is internal energy?
Energy stored in the particles in a system. It is the total amount of kinetic energy and the potential energy
Internal energy
What does a heating graph show?
When we heat a system, energy is transferred to the internal store of energy. This means that the particles will move faster so the internal energy will increase and the temperature also increases. This can be shown on a heating graph as the line increases.
Internal energy
What does a cooling graph show?
When a system is cooled, the temperature of the substance decreases, and the gradient of the line decreases.
Changes of state and specific latent heat
What is specific latent heat?
The amount of energy needed to change the state of 1kg of a substance , without a change in temperature
Changes of state and specific latent heat
What is specific latent heat of fusion and vaporisation?
- Fusion - solid to liquid (and vice versa)
- Vaporisation - liquid to gas (and vice versa)
Particle motion in gases
How do particles move in a gas?
Particles in a gas are constantly moving in random directions at random speeds.
Pressure in gases
What is pressure?
When particles move around at high speeds, they colliden with anything in their way. When particles collide with something, they exert a force on it at right angles.
Pressure in gases
How does the motion of particles effect the pressure?
The faster the particles are moving, the more frequently the particles collide with the walls of the container, the greater the force exerted on it, the greater the pressure.
Increasing the pressure of a gas
How does temperature affect pressure?
Increasing the temperature increases pressure
Increasing the pressure of a gas
How does volume affect pressure?
Increasing the volume decreases pressure
Increasing the pressure of a gas
How does speed affect pressure?
Increasing the speed increases pressure
