A gas mixture comprising of two hypothetical gases, 2.82 moles of E and 4.89 moles of F, in a 12.5-L container at 298K. What is the mole fraction of E? 0.336 0.366 mol 0.577 0.577 mol In a flask containing multiple gases (A, B and C), when the pressure is measured, this pressure reflects the TOTAL pressure (from all components) in the flask. Ptotal PA PB + Pc = Furthermore, one can calculate the pressure contribution (partial pressure) of each gas (PA, PB or Pc) by using the concept of mole fraction. Mole fraction (XA) is the number of moles of A compared to the total number of moles.. XA = BA Since the number of moles of one substance in a mixture can never be more than the total number of moles, the mole fraction for a substance always ranges between 0 (none) and 1 (all). Mole fraction is also unitless. With the mole fraction of A and the total pressure, one can calculate the partial pressure of A. Partial pressure of A=PA=Ptotal (XA) A gas mixture comprising of two hypothetical gases, 2.82 moles of E and 4.89 moles of F, in a 12.5-L container at 298K. What is the mole fraction of E?