Particle motion and pressure in gases

A teacher demonstrated how the pressure in a gas varies with temperature.

Figure 7 shows some of the apparatus used.

The teacher heated the conical flask.

The temperature of the gas in the flask increased.

How did heating the gas affect the average speed of the gas particles?

Tick () one box.

How did heating the gas affect the average kinetic energy of the gas particles?

Tick () one box.

As the temperature of the gas increased, the pressure of the gas inside the flask increased.

How did increasing the pressure affect the number of collisions each second between gas particles and the walls of the flask?

Tick () one box.

What happened to the force exerted on the walls of the flask by the gas particles when the pressure increased?

Tick () one box.

At different temperatures, nitrogen can be a gas, a liquid or a solid.

Draw one line from the state of matter to the arrangement of particles in each state.

The boiling point of nitrogen is –196 °C and the melting point of nitrogen is –210 °C.

What is the state of matter of nitrogen at a temperature of –200 °C?

Tick () one box.

What is the state of matter of nitrogen when the temperature is lower than the melting point of nitrogen?

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As a substance melts, the temperature of the substance is constant.

What happens to the kinetic energy and the potential energy of the particles as the substance melts?

Tick () one box in each row.

A scientist poured some liquid nitrogen into a container.

The container was then sealed.

Figure 10 shows the container.

The liquid nitrogen was at its boiling point.

When 9950 J of thermal energy was transferred to the liquid nitrogen, 50 g of the nitrogen turned into a gas.

Calculate the specific latent heat of vaporisation of nitrogen.

Use the Physics Equations Sheet.

Explain how the internal energy of the nitrogen changed as the nitrogen turned from a liquid to a gas.

After the nitrogen had boiled, the temperature of the gas increased.

Explain how the pressure in the container changed as the temperature increased.

A student investigated how the pressure in a fixed mass of air varies with the volume of the air.

Figure 10 shows the equipment used.

When the plunger was pushed slowly into the syringe, the temperature of the air stayed the same.

How did pushing the plunger in affect the volume of air in the syringe?

Tick () one box.

How did pushing the plunger in affect the distance between the air particles in the syringe?

Tick () one box.

How did pushing the plunger in affect the frequency of collisions between the air particles and the syringe walls?

Tick () one box.

How did pushing the plunger in affect the air pressure in the syringe?

Tick () one box.

A fire piston is a special type of syringe that can be used to start fires.

Figure 11 shows a fire piston.

The plunger is pushed quickly downwards and compresses the air.

When the air is compressed quickly, the temperature of the air increases.

How does an increase in temperature affect the mean speed of the air particles inside the syringe?

Tick () one box.

When the air is hot enough, a small piece of cotton wool in the piston catches fire.

The energy transferred to the air in the piston is 0.0130 J.

The mass of air in the piston is 2.60 × 10^–8 kg.

specific heat capacity of air = 1010 J/kg °C

Calculate the temperature change of the air.

Use the Physics Equations Sheet.

A student investigated how the pressure in a fixed mass of air varies with the volume of the air.

Figure 12 shows the equipment used.

When the plunger was pushed slowly into the syringe, the pressure in the syringe increased.

The temperature of the air remained constant.

Explain why the pressure increased.

A fire piston is a special type of syringe that can be used to start fires.

Figure 13 shows a fire piston.

The plunger is pushed quickly downwards and compresses the air.

When the air is compressed quickly, the temperature of the air increases.

How does an increase in temperature affect the air particles inside the piston?

Tick (✓) one box.

When the air is hot enough, a small piece of cotton wool in the piston catches fire.

The energy transferred to the air in the piston is 0.0130 J.

The mass of air in the piston is 2.60 × 10^–8 kg.

specific heat capacity of air = 1.01 kJ/kg °C

Calculate the temperature change of the air.

Use the Physics Equations Sheet.

A teacher demonstrated the relationship between the pressure and the volume of a fixed mass of gas at a constant temperature.

Figure 9 shows the equipment used.

Complete the sentence.

Choose the answer from the box.

Particles in a gas move in

Complete the sentence.

Choose the answer from the box.

Particles in a gas move with

Table 6 shows some of the results.

Complete Figure 10. The first point has been plotted for you.

You should:

• plot the points from Table 6

• draw the line of best fit.

The relationship between the pressure and the volume of a gas is given by the equation:

pressure × volume = constant

Calculate the constant when the pressure of the gas was 300 kPa.

Use Table 6.

When the volume of the gas increases, the pressure in the gas decreases.

The temperature of the gas stays the same.

How does increasing the volume affect each of the following quantities?

Tick (✓) one box in each row.

Figure 9 shows air being pumped into a car tyre.

Complete the sentence.

When the tyre is at the correct pressure, pumping more air into the tyre causes the pressure to increase further. The volume and temperature of the air in the tyre do not change. Explain why the pressure increases as more air is pumped into the tyre.

The air pressure in a car tyre changes if the temperature of the air in the tyre increases. Explain why.

A teacher demonstrated the relationship between the pressure in a gas and the volume of the gas.

Figure 12 shows the equipment used.

What is the range of the syringe?

Tick (✓) one box.

The relationship between the pressure and volume of a gas is given by the equation:

pressure × volume = constant

Complete the sentence.

of the gas must stay the same.

The initial volume of the gas in the syringe was 12 cm³.

The initial pressure of the gas in the syringe was 101 000 Pa.

Calculate the constant in the equation below.

pressure × volume = constant

The teacher pulled the plunger slowly outwards and the gas expanded.

The new volume of the gas was 24 cm³.

Calculate the new pressure in the gas.

The constant has the same value as in Question 08.3

Which change occurs when the plunger is pulled slowly outwards?

Tick (✓) one box.

Figure 12 shows the equipment used.

This is the method used.

1. Record the initial volume of gas in the syringe and the pressure reading before any weights are attached.

2. Attach a 2.0 N weight to the syringe.

3. Record the volume of the gas and the reading on the pressure gauge.

4. Repeat steps 2 and 3 until a weight of 12.0 N is attached to the syringe.

What was the range of force used?

Give one control variable in the investigation.

When the volume of gas in the syringe was 45 cm³, the pressure gauge showed a value of 60 kPa. Calculate the pressure in the gas when the volume of gas in the syringe was 40 cm³.

When the volume of gas in the syringe increased, the pressure on the inside walls of the syringe decreased. Explain why.

A student used the equipment in Figure 9 to investigate how the pressure of a gas varies with the volume of the gas.

The syringe is filled with air. Table 2 shows the results.

Describe how the student could use the equipment in Figure 9 to obtain the data shown in Table 2.

Describe what happens to the pressure of the air when the volume of the air is halved.

The temperature of the air in the syringe remained constant during the student’s investigation. Which two properties of the air particles would change if the temperature increased? Tick (✓) two boxes.

Figure 15 shows a balloon filled with helium gas.

Which statements describe the movement of the gas particles in the balloon? Tick (✓) two boxes.

The pressure of the helium in the balloon is 100 000 Pa.

The balloon is compressed at a constant temperature causing the volume to decrease

No helium leaves the balloon. Calculate the new pressure in the balloon.

The temperature of the helium in the balloon was increased. The mass and volume of helium in the balloon remained constant. Explain why the pressure exerted by the helium inside the balloon would increase.

A student investigated how the pressure exerted by a gas varied with the volume of the gas.

Figure 12 shows the equipment the student used.

Figure 12

A pump was used to compress the gas in a tube. As the volume of the gas 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.

Figure 13 shows the position of the student’s eye when taking volume measurements.

Figure 13

Explain what type of error would be caused if the student’s eye was not in line with the level of the liquid in the tube.

If the gas is compressed too quickly the temperature of the gas increases.

Explain how the temperature increase would affect the pressure exerted by the gas.

One of the student’s results is given below.

Calculate the volume of the gas when the pressure was 1.8 × 10⁵ Pa.

The temperature of the gas was constant.

Figure 14 shows a person using a bicycle pump to inflate a tyre.

Figure 14

The internal energy of the air increases as the tyre is inflated.

Explain why.