Chemistry
posted by Zandria .
A cylinder of argon gas contains 125 mol at a pressure of 150 atm and a temperature of 27°C. After some of the
argon has been used, the pressure is 136 atm at 27°C. What mass of argon remains in the cylinder?
A) 4.23 × 103 g B) 113 g C) 5.52 × 103 g D) 4.52 × 103 g E) 5.00 × 103 g

Since the temperature is constant, the number of moles is proportional to the pressure:
P1/P2 = n1/n2
P1 = 150 atm, P2 = 136 atm,
n1 = 125 mol, n2 = _____?
Substitute into the above equation and solve for n2 to get the moles of Ar.
Convert the moles of Ar to grams (1 mole Ar = 39.95g)