Question

Explain in terms of molecules ,the effect on the pressure of the gass if it was not given time to cool to its original temperature

Answer 1

Answer:

Volume and pressure in gases – the gas laws

Boyle’s law

Decreasing the volume of a gas increases the pressure of the gas. An example of this is when a gas is trapped in a cylinder by a piston. If the piston is pushed in, the gas particles will have less room to move as the volume the gas occupies has been decreased.

As the pressure applied to a piston is doubled, the volume inside a cylinder is halved

Because the volume has decreased, the particles will collide more frequently with the walls of the container. Each time they collide with the walls they exert a force on them. More collisions mean more force, so the pressure will increase.

When the volume decreases, the pressure increases. This shows that the pressure of a gas is inversely proportional to its volume.

This is shown by the following equation - which is often called Boyle’s law. It is named after 17th century scientist Robert Boyle.

P1V1 = P2V2

where:

P1 is the initial pressure

V1 is the initial volume

P2 is the final pressure

V2 is the final volume

It can also be written as:

pressure1 × volume1 = pressure2 × volume2

Note that volume is measured in metres cubed (m3) and temperature in kelvin (K).

It means that for a gas at a constant temperature, pressure × volume is also constant. So increasing pressure from pressure1 to pressure2 means that volume1

Question

A sealed syringe contains 10 × 10-6 m3 Pa. The plunger is pushed until the volume of trapped air is 4 × 10-6 m

Reveal answer

Charles’ law

Charles’ law describes the effect of changing temperature on the volume of a gas at constant pressure. It states that:

volume1=volume2×temperature1temperature2

V1=V2×T1T2

where:

V1 is the initial volume

V2 is the final volume

T1 is the initial temperature

T2 is the final temperature

Note that volume is measured in metres cubed (m3) and temperature in kelvin (K).

This means that if a gas is heated up and the pressure does not change, the volume will. So for a fixed mass of gas at a constant pressure, volume ÷ temperature remains the same.