5th Ideal Gasses Follow up

A diver breathes air from a cylinder when he is under water.

The cylinder contains 8 litres of air at 200 times atmospheric pressure.

The air is released from the cylinder at normal atmospheric pressure.

The diver needs 16 litres of air per minute.

Calculate the maximum amount of time that the diver can breathe under water using this cylinder.

(3)

• 25 minutes

• 100 minutes

• 25 seconds

• 100 seconds

When a diver breathes out, bubbles are released.

Suggest why the bubbles expand as they rise to the surface.

Choose all that apply:

• Pressure decreases as depth decreases

• Pressure increases as depth decreases

• p/v is constant

• p x v is constant

Explain how Brownian motion provides evidence that air is made of small particles. Pick the best answer

• Smaller air molecules are jostled by faster larger smoke particles providing a continuous random motion of smaller air molecules

• Larger smoke particles are jostled by faster smaller air molecules providing a continuous random motion of air molecules

• Larger smoke particles are jostled by faster smaller air molecules providing a continuous random motion of smoke particles

• Smaller air molecules are jostled by faster larger smoke particles providing a continuous random motion of smoke particles

In a bicycle pump, when the piston handle is pulled, air moves past the flexible rubber disc into a sealed space.

When the volume of the space is 80 cm³, the air has a pressure of 1.01×10⁵ Pa.

Calculate the pressure inside the space when the piston handle is pushed in and the volume decreases to 10 cm³.

• 8.08x10⁵ kN/m²

• 8.08x10⁵ Pa

• 1.2x10⁴ Pa

• 1.2x10⁴ kN/m²

A cylinder of compressed air used to breathe underwater.

Explain how the air causes a pressure on the inside of the cylinder.

• Particles collide with each other, producing a force and pressure = force/area

• Particles collide with each other, producing a pressure and pressure = force/area

• Particles collide with the walls of the can, producing a force and pressure = force/area

• Particles collide with the walls of the can, producing a pressure and pressure = force/area

Explain what happens to the pressure of the air inside a sealed cylinder as its temperature increases.

• There is an increase in the speed. Particles collide with the walls more often with more force.

• There is an increase in the kinetic energy and therefore the average speed decreases. Particles collide with the walls more often with more force.

• There is an increase in the kinetic energy and therefore the average speed decreases. Particles collide with the walls less often with more force.

• There is an increase in the kinetic energy and therefore the average speed increases. Particles collide with the walls more often with more force.

The gas in a cylinder has a pressure of 210 kPa at a temperature of 20 °C.

Calculate the new pressure when the temperature of the gas rises to 83 °C.

• 50.6 kPa

• 871.5 kPa

• 172.8 kPa

• 255 kPa

What happens to the pressure and volume of a cylinder of trapped air if the pump handle is pushed in

• Pressure Decreases, Volume Decreases

• Pressure Increases, Volume remains the same

• Pressure Decreases, Volume remains the same

• Pressure Increases, Volume decreases

The temperature of a gas is directly proportional to:

• Average velocity and kinetic energy of the particles

• Average velocity of the particles

• Average kinetic energy of the particles

• Neither average velocity or kinetic energy of the particles

What happens to the pressure and volume of a cylinder of trapped air if the cylinder is heated

• Pressure decreases, volume decreases

• Pressure increases, volume increases

• Pressure decreases, volume remains the same

• Pressure increases, volume remains the same