A 3 mole sample of gas at 25 degrees C and 1 atm, leaks. When the leak is discovered and sealed the pressure in the vessel has dropped to 0.694 atm. How many moles of gas remain in the vessel?

Answer 1

Basically, you are told that the initial pressure is 1 atm and after the leak, the final pressure is 0.694 atm. The temperature did not change. The the volume of the contained did not change. The only thing that changed is the number of moles of gas. Recall that P1V1/T1n1 = P2V2/T2n2 where P1, V1, T1 and n1 are the initial pressure, volume, temperature and moles, respectively and P2 , V2, T2 and n2 are the final pressure, volume, temperature and moles respectively. Since the temperature and volume are constant, we are left with

P1/n1 = P2/n2 and plugging in the values we have...

1 atm/3 moles = 0.694 atm/x moles

x = 2.08 moles = 2 moles

Thus, 2 moles of gas remain (to 1 significant figure)

Answer 2

Write the given in math form, including units. V= P= T= Then I will guide you through the problem.