1.18 A. we know that mole fraction of oxygen in air = 0.21 partial pressure of o

Question

1.18

A.

we know that mole fraction of oxygen in air = 0.21

partial pressure of oxygen(PO2) = PT x YO2 = PT x 0.21

PT = total pressure

YO2 = mole fraction of oxygen

PO2 = 110mmHg = PT x 0.21

PT = 523.81 mmHg Ans (a)

(b)

for any gas

P1V1 /n1T1 = P2V2/n2T2

where P is pressure

V = volume

n = moles of gas

T = temperature

subscript 1 and 2 represents conditions at two situation

given P1 = P2 same pressure

T1 = T2 same temperature

P1V1 /n1T1 = P1V2/n2T1

n2 = V2/V1 x n1 = 10.5 L / 42.0 L x 1.7 mol = 0.425 mol

1.21

when no. of moles is same that is n1 = n2 when there is no leakage of gas

according to ideal gas equation

P1V1 /T1 = P2V2/T2

20 oC = 273 + 20 = 293 K = T1

-50 oC = 273 - 50 = 223 K = T2

P1 = 760 mmHg

P2 = 76 mmHg

V1 = 5.00L

V2 = P1V1 T2/T1 P2 = 760 mmHg x 5.00 L x 223K / (293 K x 76 mmHg) = 38.05 L

similarly as above

T1 = 293 K

T2 = 34 + 273 = 307K

V1 = 5.00 L

V2 = 2.40 L

P1 = 365 mmHg

P2  = P1V1 T2/T1 V2 = 365 mmHg x 5.00 L x 307 K / (293 K x 2.40 L) = 796.75 mmHg

Ans = 796.75 mmHg

Explanation / Answer

1.18

part A) If the partial pressure of oxygen drops below 110 mmHg , passengers become drowsy. If this happens, oxygen masks are released. What is the total cabin pressure at which oxygen masks are dropped?

part B) A sample of gas in a cylinder as in the example in Part A has an initial volume of 42.0 L , and you have determined that it contains 1.70 moles of gas. The next day you notice that some of the gas has leaked out. The pressure and temperature remain the same, but the volume has changed to 10.5 L . How many moles of gas (n2) remain in the cylinder?

1 21 a) A very flexible helium-filled balloon is released from the ground into the air at 20. C. The initial volume of the balloon is 5.00 L, and the pressure is 760. mmHg. The balloon ascends to an altitude of 20 km, where the pressure is 76.0 mmHg and the temperature is 50. C. What is the new volume, V2, of the balloon in liters, assuming it doesn't break or leak?

b) Consider 5.00 L of a gas at 365 mmHg and 20. C . If the container is compressed to 2.40 L and the temperature is increased to 34 C , what is the new pressure, P2, inside the container? Assume no change in the amount of gas inside the cylinder.

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