The passage below is about kinetic theory.
Complete the sentences.
Molecules in a gas are in constant random motion at ............... speeds.
Random motion means that the molecules do not travel in a specific path and undergo sudden changes in their motion if they collide with the ............... of its container or with other ................. .
The ................ of the gas is related to the average kinetic energy of the molecules.
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A sealed boiling tube as shown in Figure 2 contains some gas.
The boiling tube is heated.
Figure 2
State what happens to the particles of gas as the temperature increases.
The boiling tube is then placed in an ice bath.
State what happens to the speed and the kinetic energy of the particles in the gas.
On the axes below, sketch a graph of pressure against temperature for a constant volume of gas. Clearly mark the value of absolute zero on your graph.
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Figure 1 shows some gas particles in a container.
The piston can be moved in or out to change the volume of the gas.
Figure 1
Add arrows to the diagram to show the motion of the gas particles.
Explain how the motion of the gas particles produces a pressure inside the container.
State what would happen to the pressure if you pushed the piston into the container without changing the temperature.
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The student wants to investigate gas pressure further. They blow up two balloons to the same size.
They put one balloon into a freezer.
After a while, the student compares the two balloons and finds that the balloon that has been cooled is smaller.
Explain why the cooled balloon is smaller using ideas about particles.
The student decides to investigate the link between temperature and the size of the balloon.
They write a plan for this experiment:
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I will change the temperature of the balloon by putting it into a freezer. To get a range of different temperatures I will put the balloon into the freezer for different times. I will measure the temperature of the balloon using a thermometer. To measure the size of the balloon I will take it out of the freezer and line it up next to a ruler. To make sure it is a fair test I will repeat the experiment three times. I will plot a graph of size against temperature. |
There are several faults in the student's plan.
Identify three of these faults and suggest an improvement to correct each one.
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Figure 1 is a graph showing how the volume changes with pressure for a gas at a constant temperature.
Figure 1
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A student carried out an investigation to see how the pressure of a gas varied with its volume.
Figure 1 shows the apparatus used.
Figure 1
The student presses down on the syringe.
As the volume of the gas in the syringe decreases, the pressure of the gas increases.
The student only recorded one set of results.
Give two reasons why taking repeat readings could provide more accurate data.
If the student pushes the plunger too quickly, the temperature of the gas increases.
Explain how the increased temperature would affect the pressure exerted by the gas.
The student records the following results:
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105 PaThe student then expands the gas at a constant temperature by raising the plunger slowly.
Calculate the pressure when the volume of the gas is 50 cm3.
A car tyre is inflated using a foot pump.
Explain why the internal energy of the air in the tyre increases as it is inflated.
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A student carries out an investigation to measure how the pressure of a gas changes as its volume changes.
Her results are shown in Figure 2 below.
Figure 2
What conclusion can be drawn from the data in the graph?
Use data from the graph in your answer.
Give the reason for your answer.
Explain, in terms of particles, why the pressure in the gas increases as its volume decreases.
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Using ideas about particles, explain how air inside a container exerts pressure.
A car tyre exerts a pressure of 203 kPa on the ground.
The contact area between the tyre and the ground is 0.021 m2.
Calculate the force that the tyre exerts on the ground.
The air in the tyre heats up when the car is driven.
Explain how this affects the contact between the tyre and the ground.
You should assume that the volume of the air remains constant.
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Figure 3 below shows the basic details of the steam engine used in a steam locomotive.
Figure 3
The following is a description of how the steam engine works:
Explain why the pressure of the steam increases as its temperature increases.
When the inlet valve is opened, the steam moves into the cylinder.
The pressure of the steam is 1.53 MPa.
The area of the piston is 0.0285 m2.
Calculate the force exerted by the steam on the piston.
When the steam flows through the outlet valve, its pressure changes from 1.53 MPa to 101 kPa.
The volume of steam in the cylinder is 0.022 m3
Calculate the volume of the steam after it has passed through the outlet valve.
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Figure 4 shows the particles of helium inside a balloon.
Figure 4
Describe the motion of particles inside the helium balloon
A small canister of pressurised helium is used to fill some balloons.
Using ideas about particles, explain why the pressure in the canister decreases as the helium is used to fill the balloons.
The cannister supplies 20 000 cm3 of helium at a pressure of 2400 kPa.
The volume of each balloon is 1200 cm3.
The pressure inside a balloon is atmospheric pressure, 100 kPa.
Calculate how many balloons can be filled using the helium from the canister.
You should assume the temperature of the helium remains constant.
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