We are given:
Volume of gas = 3.8 L
Pressure = 460 mmHg
Temperature = 77°c = (77+273)K = 350K
Converting the pressure to atm:
Pressure(in atm) = Pressure(in mmHg) / 760
Pressure = 460/760 = 0.6 atm
Finding the number of moles:
using the ideal gas equation:
PV = nRT [where R is the universal gas constant]
replacing the given values in this equation
(0.6)(3.8) = n(0.082)(350)
n = (0.6*3.8)/(0.082*350)
n = 0.08 moles
