A flexible container at an initial volume of 5.120 L contains 8.500 mol of helium. More
helium is then added to the container until it reaches a final volume of 18.10 L. Assuming
the pressure and temperature of the gas remain constant, calculate the number of moles of
helium added to the container. Calculate the mass of helium added.
Moles of Helium;
Mass of helium=86.2g