Kinetic Particle Model of Matter

A liquid occupies a much smaller volume than a gas which has the same number of molecules.

Explain why there is this difference.

State the formula that relates $V_1$, $V_2$, $p_1$ and $p_2$.

The initial pressure of the gas in the cylinder is $1.2 \times 10^5\ \text{Pa}$ and its initial volume is $100\ \text{cm}^3$. The cross-sectional area of the piston is $5.0\ \text{cm}^2$.

The piston is pushed in a distance of $8.0\ \text{cm}$.

Calculate the final pressure of the gas in the cylinder.

Explain, using ideas about molecules, why the pressure of the gas changes.

Describe, in terms of the molecules, three ways in which a gas differs from a liquid.

1. ______
2. ______
3. ______

In order to keep the liquid boiling, it is necessary to keep the hotplate switched on.

Explain why energy must be supplied in order to turn a liquid at its boiling point into a gas.

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

When the aircraft is on the ground, the pressure of the air inside the aircraft is $100\ \text{kPa}$.

Calculate the volume of air inside the bag when the aircraft is on the ground.

volume = ______

State two assumptions that you made in your calculation in (b)(i).

1. ______
2. ______

Fig. 5.1 shows the arrangement of the molecules in the solid.

In the space below, draw the arrangement of the molecules in the liquid.

Complete the table by describing the motion of the molecules in the solid, liquid and gas.

Suggest why a gas is able to fill a container but a solid has a fixed shape.

Explain, in terms of the molecules, how the gas exerts a pressure on the inside of the syringe.

The piston is slowly pulled to the right until the volume occupied by the gas is $110\text{ cm}^3$. The temperature of the gas does not change.

Calculate the new pressure of the gas.

pressure = ______

Explain, in terms of molecules, why the pressure of the trapped gas increases.

The rod is pulled down and the piston is then free to move as shown in Fig. 6.2.

As the piston moves, the temperature of the gas remains constant.

State and explain, in terms of molecules, what happens to the pressure of the gas.

Explain, in terms of molecules, how the air inside the cylinder exerts a pressure.

When the boat is fully inflated, a valve is closed trapping the air in the rubber chamber. The air pump is disconnected.

The man sits on the side of the boat. The volume of the rubber chamber decreases and the pressure of the air in the rubber chamber increases. The temperature of the air stays constant.

Explain, in terms of molecules, why the pressure increases.

why a balloon filled with gas expands when heated,

why a balloon filled with water expands very little when heated.

A bubble of gas rises from the bottom of a lake to the surface. The pressure at the bottom of the lake is $3.0 \times 10^5\ \text{Pa}$ and the pressure at the surface is $1.0 \times 10^5\ \text{Pa}$. The volume of the bubble at the bottom of the lake is $2.0\ \text{cm}^3$.

Calculate the volume of the bubble at the surface.

volume = ______

State one assumption that you have made in your calculation in (i).

State the equation that relates the volume $V_2$ of the helium in the balloon at launch to $p_1$, $p_2$ and $V_1$.

______

Calculate $V_2$.

$V_2$ = ______

When it leaves the ground, the balloon is only partially inflated. Suggest and explain why this is necessary.

Explain, in terms of molecules, why the pressure of the air inside the can decreases as it is used.

A student uses an inverted measuring cylinder in a water trough to measure the volume that the air occupies at atmospheric pressure. Fig. 2.2 shows the equipment.

Initially the inverted measuring cylinder is full of water.

The student presses the top of the can and air passes through the rubber tubing into the inverted measuring cylinder. The air gradually replaces the water in the cylinder until no more air can leave the can. The final temperature of the air is equal to its initial temperature.

The volume of the air inside the can is $1.8 \times 10^{-4}\text{ m}^3$.

The student observes that, at an atmospheric pressure of $1.0 \times 10^5\text{ Pa}$, the total volume of the air in the measuring cylinder, the can and the tubing is now $9.4 \times 10^{-4}\text{ m}^3$.

Determine the original pressure of the air in the can.

pressure = ______