SCH3U – Quiz # 4

A balloon that contains 31.2 L of helium gas, at 98 kPa, is released and rises into the

atmosphere. What is the new pressure, in atm, of the balloon when it eventually fills up to a

new volume of 129.8 L?

What would be the new volume if the temperature on 150 mL of a certain gas is

changed from 40oC to -5oC?

When you walk up a mountain, your ears feel strange. What are you feeling and WHY?

Why is it a terrible idea, when deep-sea diving, to rise back to the surface at a quick rate?

A balloon that contains 31.2 L of helium gas, at 98 kPa, is released and rises into the

atmosphere. What is the new pressure, in atm, of the balloon when it eventually fills up to a

new volume of 129.8 L?

P1V1 = P2V2

(98 kPa)(31.2 L) = P2(129.8 L)P2 = 23.6 kPa

1 atm = x 101.3 kPa 98 kPa x = 0.97 atm

What would be the new volume if the temperature on 150 mL of a certain gas is

changed from 40oC to -5oC?

V1 = V2T1 T2150 mL = V2313 K 268 KV2 = 128 mL

When you walk up a mountain, your ears feel strange. What are you feeling and WHY?

• Your ears may pop or your eardrums may feel as if it’s expanding (which it is!)

• Boyle’s Law says that as pressure ↓, volume ↑

• Pressure on ground is 1 atm. As you move upwards into the atmosphere, the pressure ↓ (air is less dense due to particles being further apart). The ↓ in pressure causes an ↑ in volume!

Why is it a terrible idea, when deep-sea diving, to rise back to the surface at a quick rate?

• As previously stated, Boyle’s Law says as pressure ↑, volume ↓

• When deep-sea diving, the pressure is very great due to the force of gravity pushing air+water on top of you. This pressure ↑ causes the volume of your body’s organs (eg. Lungs, liver) to ↓

• When you swim back up, the pressure ↓, causing your body’s organ to ↑ in volume. But you have to go slowly. If you ascend too fast, the gases in your blood will burst out into solution, like opening up a can of pop. You must acclimatize at certain levels before continuing to ascend. = THE BENDS