P6.7 Gas pressure and volume

Question 1

How does a piston get pushed into a tube?

Answer 1

Work must be done by applying a force to the piston - applied force has to overcome the force that is caused by the pressure of the gas enclosed in the tube

Question 2

What would happen if compression did not happen slowly when a piston is pushed into a tube?

Answer 2

Work done on the gas would increase its internal energy store and its temperature

Question 3

Why do you compress the gas slowly?

Answer 3

Gas loses energy by heating its surroundings at the same rate as energy is transferred into it - so the internal energy store and the temperature of the gas do not change

Question 4

Why does the gas pressure increase when the volume is decreased?

Answer 4

The space the molecules move in is smaller so they don’t travel as far between each impact with the surface of their container

Molecules also hit the surface more often - so pressure increases

Question 5

What is Boyle’s law?

Answer 5

For a fixed mass of gas at constant temperature pressure x volume = constant

Question 6

What is the equation for Boyle’s law?

Answer 6

Pressure, p x volume , v = constant

Pa x m^3 = constant