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1. Assume that you have a cylinder with a movable piston. What would happen to t

ID: 913567 • Letter: 1

Question

1. Assume that you have a cylinder with a movable piston. What would happen to the gas pressure inside the cylinder if you do the following?

A. Decrease the volume to one-fourth the original volume while holding the temperature constant. Express your answer in terms of the variable Pinitial.

B. Reduce the Kelvin temperature to half its original value while holding the volume constant. Express your answer in terms of the variable Pinitial.

C. Reduce the amount of gas to half while keeping the volume and temperature constant. Express your answer in terms of the variable Pinitial.

2. The typical atmospheric pressure on top of Mt. Everest (29,028 ft) is about 265 torr. Convert this pressure to

A. mmHg

B. pascals

C. bars

Explanation / Answer

1)

A) we know that the pressure is inversely proportional to volume exerted by gas: So if we decrease the volume to one fourth the original volume then the pressure will increases four times

Let us say initial pressure = P1 Initial volume = V1

Final pressure = P2 final volume = V1/4

So P1V1 = P2V2   (at constant pressure)

P1V1 = P2V1/4

So P2 = 4X P1

B) The Pressure is directly proportional to temperature

So at constant volume if we reduce the kelvin temperature to half of its original value then the pressure will also gets reduced half.

C) The pressure volume and temperature has following relation

PV = nRT

n = number of moles

At constant temperature and volume

Pressure will be directly proportional to number of moles of gas

So if the moles will reduce half to its original value then the pressure will also reduce to half.

2)

We know that

A) 1 torr = 1mmHg

so 265Torr = 265 mmHg

B) 1 torr = 133.32 pascals

So 265 torr = 265 X 133.32 pascals = 35329.8 pascals

C) 1 torr = 0.00133 bars

So 265 torr = 265 x 0.00133 bars = 0.352 bars