Question

A rigid tank contains 65.5 g of chlorine gas (Cl2) at a temperature of 73 °C and an absolute pressure of 5.60 × 105 Pa. Later, the temperature of the tank has dropped to 33 °C and, due to a leak, the pressure has dropped to 3.50 × 105 Pa. How many grams of chlorine gas have leaked out of the tank? (The mass per mole of Cl2 is 70.9 g/mol.) Answer in grams. Please provide a detailed answer. Thank you!

Answer 1

Given

   initial --

chlorine in the tank is at Temperature T1 = 73 °C = 346 k

           pressure P1 = 5.6*10^5 Pa

           number of moles n1 = 65.5/70.9 = 0.924

final
   Temperature T2 = 33 0C = 306 k,
   pressure P2 = 3.5*10^5 Pa

  
from ideal gas equation PV = nRT

   P1/P2 = n1 T1/n2T2 (V is constant)

   n2 = n1*T1*P2/(P1T2)

substituting the data

   n2 = (65.5/70.9)(346*3.5*10^5/5.6*10^5*306)
   n2 = 0.65287457249

molar massof chlorine is 70.9 g/mol, the mass , amount of the gas remained in the tank is

   0.65287457249*70.9 g = 46.29 g

the amount of chlrine leaked from tank is 65.5 g - 46.29 g = 19.21 g