5. A 1.00-L balloon contains 36.7 moles of He gas. What would be the volume of the balloon when gas is removed until it contains 2.451 moles of gas?

66.8 ml Assuming that the pressure remains constant, we can use the ideal gas law which is PV=nRT where P = pressure V = volume n = number of moles R = Ideal gas constant T = absolute temperature Since in this problem we're keeping R, T, and P constant, we can eliminate them from consideration, so V=n which means that volume will be proportional to number of moles. So we have the following ratio 2.451/36.7 = X/1 0.066784741 = X/1 0.066784741 = X So the volume of the balloon will be 0.066784741 liters, or 66.784741 ml Rounding to 3 significant figures gives 66.8 ml