Kinetic Particle Model of Matter (Cambridge O Level Physics)

Some gas molecules are in a box at room temperature.

                            
Fig. 3.1 shows the position of some of the molecules and the direction of movement of each molecule.

The gas in Fig. 3.1 is cooled. The gas turns into a liquid then into a solid.

State how the average separation of molecules in the gas is different from the average separation of molecules in the solid.

Describe the movement of the molecules in

Extended

A closed box contains gas molecules.

Explain, in terms of momentum, how the molecules exert a pressure on the walls of the box.

Fig. 5.1 shows a metal can containing air. The can is sealed with a lid.

The air in the can exerts a pressure of 20 000 N/m² on the lid. The area of the can lid is 0.09 m².

Calculate the force on the lid due to the air in the can.

force = ...................................................... N 

The air in the can becomes warmer.

State and explain what happens to the pressure of the air in the can. Use your ideas about gas molecules.

Fig. 4.1 represents an atom.

(i)

on Fig. 4.2, the arrangement of atoms in a crystalline solid,

[1]

 

(ii)

on Fig. 4.3, the arrangement of atoms in a gas.

[1]

A helium-filled balloon in the room of a house suddenly bursts.

State and explain, in terms of atoms, what happens to the helium from the balloon after the balloon has burst.

Match each description with the correct state of matter in Table 4.1.

Write the correct letter in Table 4.1.

A – Molecules move around freely and are far apart from each other.

B – Molecules vibrate about fixed positions.

C – Molecules move around randomly and are close to each other.

Some students heat water in a beaker. They measure the temperature every minute. They heat the water for 8 minutes until it boils, and then continue to heat it for a further 5 minutes.

Describe and explain how the temperature of the water changes during the 13 minutes.

A passenger in an aircraft seals some air inside a plastic bag.

Fig. 3.1

Explain how the particles of air in the bag exert a pressure on the inside of the bag.

When the bag is closed, the pressure of the air inside the aircraft is 80 kPa and the bag contains 500 cm³ of air.
 

volume = ................................................... cm³ [2]
 

[1]

The point plotted on the graph in Fig. 3.2 shows the initial pressure and volume of the air inside the bag.

Sketch a line on Fig. 3.2 to show how the volume of the air changes as the pressure increases.

Fig. 3.2

Describe qualitatively, in terms of particles, the effect on the pressure of a fixed mass of gas in a container when there is:

Table 1.1 gives a series of pressures and their corresponding volumes, obtained in an experiment with a fixed amount of gas. The gas obeys the law for a fixed amount of gas at a constant temperature.

 Table 1.1 

Air is trapped by a piston in a cylinder. The pressure of the air is 7.1 × 10⁵ Pa. The distance from the closed end of the cylinder to the piston is 48 mm.

The piston is pushed in until the pressure of the air has risen to 9.0 × 10⁵ Pa.

Calculate how far the piston has moved.

Fig 1.1 shows the graph showing how the volume changes with pressure for a gas at a constant temperature

Fig 1.1

Sketch the graph for the same gas at a higher temperature.

Sketch the graph of

(i)

Pressure p against  where V is the volume of a gas. Label this X.

[2]

(ii)

The graph in part (i) but with the gas at a higher temperature. Label this Y.

[1]

The piston in Fig 1.2 is pulled out of the cylinder from position A to position B, without changing the temperature of the air enclosed. Position B is double the length of the distance between position A and the end of the cylinder. The pressure when the piston is at position A is 2.5 × 10⁵ Pa.

Calculate the pressure when the piston is moved to position B.