Chapter U3.12, Problem 8E

Interpretation Introduction

Interpretation: The information regarding the decrease in pressure with increase in altitude on floating of helium up in the sky is given. The effect on the volume of the balloon has to be explained.

Concept introduction: The ideal gas equation is given below.

  $\text{PV}=n\text{RT}$

Here, P is pressure of gas, V is volume, n is number of moles of gas, T is temperature and R is universal gas constant.

At conditions of constant temperature and number of moles, pressure and volume vary inversely with respect to each other.

Answer to Problem 8E

The volume of the balloon increases with decrease in pressure at high altitude due to increased inside pressure of the gas.

Explanation of Solution

The pressure of the outside gas is more at the sea level then at the high altitudes. Now when a balloon floats high in sky then pressure at altitudes decreases but the molecules of gas inside the balloon are still in motion and thus, they exert the force over the walls of the balloon. As there is no outside pressure; therefore, the push on balloon from outside air will be negligible. This will lead to an expansion of the gas and it will ultimately increase the volume of the balloon.

Conclusion

The volume of the balloon increases with decrease in pressure at high altitude due to increased inside pressure of the gas.