Part A: A very flexible helium-filled balloon is released from the ground into t

Question

Part 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? Express your answer numerically in liters.

Part B: Consider 4.20 L of a gas at 365 mmHg and 20. C . If the container is compressed to 2.50 L and the temperature is increased to 32 C , what is the new pressure, P2, inside the container? Assume no change in the amount of gas inside the cylinder. Express the pressure numerically in millimeters of mercury.

Explanation / Answer

A) we know that

PV = nRT

here

the amount of helium constant

so

PV / T = constant

at two conditions

we get

P1V1 / T1 =P2V2 / T2

given

P1 = 760

V1 = 5

T1 = 20 C = 293 K

P2 = 76

T2 = 223 K

so

760 x 5 / 293 = 76 x V2 / 223

V2 = 38

so

the new volume of the balloon is 38 L

B)

now

P1V1 / T1 = P2V2 / T2

given

P1 = 365

V1 = 4.2

T1 = 293 K

V2 = 2.5

T2 = 305 K

so

365 x 4.2 / 293 = P1 x 2.5 / 305

P1 = 638.3

so

the new pressure inside the cylinder is 638.3 mm Hg

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