Question

On a summer day early in the morning, a balloon is filled with helium when the temperature is 21°C, but the temperature will reach a peak of 46°C later in the day. The balloon holds 12.8 L of helium gas at a starting pressure of 239 kPa. The balloon will burst when the internal pressure (Pb) reaches 256 kPa. Answer the following questions and show your work. How many moles of helium gas are in the balloon? What will the gas pressure be in the balloon at the peak temperature? Will the balloon burst when the temperature reaches 42°C? Explain. To what pressure should the helium gas pressure be reduced to avoid bursting of the balloon? (Assume no significant volume change of the balloon.)

Answer 1

Will the balloon burst when the temperature reaches 42°C? Explain.

Repeat this last calculation with T2 = 315, and compare that pressure to 256 kPa (the pressure at which the balloon bursts).

P1/T1 = P2/T2

239kPa/294 K = P2 / 315

P2 = 256.1 kPa.

Since this is just over 256 kPa, the balloon will burst.

To what pressure should the helium gas pressure be reduced to avoid bursting of the balloon? (Assume no significant volume change of the balloon.)

I would repeat this same calculation using 256 for P2, and calculate what P1 should be.