Properties of Matter Flashcards
What is specific heat capacity?
The number of Joules of energy needed to raise 1kg of a substance by 1°C.
What is meant by temperature?
It is a measure of the mean kinetic energy of the particles
What is meant by heat?
It is the energy of the substance.
What is conservation of energy?
Energy cannot be created or destroyed it can only be transferred from one type to another
What is latent heat of vaporisation?
The number of Joules of energy required to change 1kg of a liquid to 1kg of a gas with no temperature change.
What is latent heat of fusion?
The number of Joules of energy required to change 1kg of a solid to 1kg of a liquid with no temperature change.
Suggest a way that we say ‘energy is lost’ (not converted to the type of energy we want)?
- Heat lost to the surroundings due to friction
- Sound energy lost to air because of vibrations
- Energy lost as heat to the surroundings
- Heat lost in heating up a container instead of the substance in it
What is meant by pressure?
The force per unit area
Explain how snow shoes prevent you sinking into the snow.
Snow shoes have a large area. So the force of the person (weight) is spread over a larger area so the pressure exterted on the snow is less as P = F/A
These two block of wood have identical mass. Explain which exerts the greatest pressure.
- Both blocks have the same mass, so as W=mg will exert the same force down on the surface.
- Block B is sitting so that a small area sits on the surface, so as P = F/A it will exert a larger pressure.
Explain why being stood on by a stilletto heel is painful.
Stileto heels have very small areas. So the force of the person (weight) is spread over a very small area so the pressure exterted is high as P = F/A
What causes pressure of a gas in a container?
Gas particles hitting the sides of a container
Using Kinetic Theory explain what happens to the pressure if you increase the temperature of a fixed mass gas in a fixed volume container?
- Pressure is caused by particles hitting the sides of the container.
- The temperature is increased. The particles gain kinetic energy.
- They will move faster and so hit the sides of the container more often and with a greater velocity / force.
- So the pressure increases.
Using Kinetic Theory explain what happens to the pressure if you decrease the volume of a fixed mass gas at a constant temperature?
- Pressure is caused by particles hitting the sides of the container.
- The volume is decreased. The particles have less room to move about and so hit the sides of the container more often.
- So the pressure increases.
Using Kinetic Theory explain what happens to the volume if you increase the temperature of a fixed mass gas at a fixed pressure?
- Pressure is caused by particles hitting the sides of the container.
- The temperature is increased. The particles gain kinetic energy.
- They will move faster and so hit the sides of the container more often and with a greater velocity/force.
- So the pressure increases.
- This puts pressure on a rubber bung/bead of mercury etc. and it moves. It will move until the pressure inside the container = pressure outside the container.
- So the volume will increase.
What is meant by absolute zero?
- When gas particles have no energy and cannot move or collide with the sides of the container.
- They have no more kinetic energy to remove.
- Temperature cannot go below this.
What temperature does absolute zero occur at?
0 K or -273 °C
How can you convert between °C (degrees Celsius) and K (Kelvin)?
Temperature in degrees Celsius + 273
What is the energy change in a buzzer?
Electrical to sound
Two 1kg blocks of metal are heated up. Block A and Block B. Each block is made from a different material. They are both supplied with 10000J on energy. Block B has the biggest temperature change.
What can you say about Block B compared to Block A?
Block B has a lower specific heat capacity
A temperature - time graph is shown below. What is happening at point B on the graph?
- The material is changing state.
- From solid to liquid
A temperature - time graph is shown below. What is happening at point D on the graph?
- The material is changing state
- From a liquid to a gas.
A temperature - time graph is shown below. What is happening at point A on the graph?
The temperature of the solid material is rising.
A temperature - time graph is shown below. What is happening at point C on the graph?
The temperature of the liquid is increasing.
A temperature - time graph is shown below. What is happening at point E on the graph?
The temperature of the gas is increasing.
The graph below shows a temperature - time graph. Points B and D show changes in state. Explain why this can be identified from the graph.
When a substance changes state the temperature remains constant. (Shown by horizontal line on graph)
Describe an experiment to investigate the relationship between the the pressure and the volume of a fixed mass of gas, at a constant temperature.
Boyles Law:
- Pump is used to put pressure on oil which puts pressure on a fixed mass of trapped gas.
- Valve is closed.
- Volume of air column is read off the scale.
- Pressure is read off the bourdon gauge.
- Valve is opened and closed to change the pressure to get a set of readings.
- Draw graph of pressure against volume.
Describe an experiment to investigate the relationship between the temperature and the pressure of a fixed mass of gas, with a fixed volume.
- Place the flask in a beaker of water.
- Heat the water.
- As the water heats up take a set of readings.
- The temperature of the water from the thermometer
- The pressure of the gas from the bourdon gauge
- Draw graph of pressure against temperature
Describe an experiment to investigate the relationship bewteen the volume and the temperature of a fixed mass of gas at a fixed pressure.
- A fixed mass of gas is trapped by a bead of mercury
- Place the capilary tube, thermometer and ruler/scale into the beaker of water.
- Heat the water.
- At different temperatures - measure the temperature of the gas from the thermometer and the volume from the ruler/scale.
- The pressure is kept constant as the bead of mercury is free to move so that the pressure reamins constant.
- Plot a graph of volume against temperature.
