Question

A balloon vendor at a street fair is using a tank of helium to fill her balloons. The tank has a volume of 113.0 L and a pressure of 122.0 atm at 25.0 °C. After a while, she notices that the valve has not been closed properly. The pressure had dropped to 112.0 atm (The tank is still at 25.0 °C).

Answer 1

Given Data:
                   P₁  =  122 atm

                   P₂  =  112 atm

                   V₁  =  113 L

                   V₂  = ?

Solution:
              Let suppose the gas is acting ideally. According to Ideal gas equation, keeping the temperature constant,

                                  P₁ V₁  =  P₂ V₂
Solving for V₂,
                                      V₂  =  P₁ V₁ / P₂
Putting Values,
                                      V₂  =  (122 atm × 113 L) ÷ 112 atm
                 
                                      V₂  =  113 L

Converting Volume to Moles,
 As,
                         22.4 L is occupied by  =  1 mole of He gas
So,
                         113 L will occupy        =  X moles of He gas

Solving for X,
                                     X  =  (113 L × 1 mole) ÷ 22.4 L

                                     X  =  5.04 Moles of He