A balloon filled with helium gas at 20°C occupies 2.91 L at 1.00 atm. The balloon is immersed in liquid nitrogen at -196°C, raising the pressure to 5.20 atm.

Question

What is the volume of the balloon in the liquid nitrogen?

Answer 1

Hi Elle! The first thing we need to do is solve for the moles of helium in the balloon. To do this, we use the equation PV = nRT. Rearrange the equation so that n = PV/RT, where P = 1 atm, V = 2.91 L, R = 0.0821 atm x L/K x mol, and T = 293 K. Doing this calculation results in 0.12 moles of helium in the balloon.

Now, we use the same equation rearranged to solve for volume, V = nRT/P. This time, our temperate (T) has changed to 77 K, and our pressure has changed to 5.2 atm. Doing this calculation results in our final answer of 0.146 L. Hope this helps!