Answer:
Total pressure = 10 atm
Explanation:
The excersise can help to understant the concept of mole fraction
Mole fraction is defined as:
moles of gas / Total moles = pressure of that gas / Total pressure
Both can be summed.
Sum of moles of each gas in the mixture = Total moles
Sum of pressures of each gas in the mixture = Total pressure
Those, are laws for gases.
Total moles: 3 mol of gas A + 4 moles of gas B + 5 moles of C
= 12 total moles
Pressure of A is 2.5 atm.
We replace data at the mole fraction relation
moles of A / total moles = Pressure of A / Total pressure
3 moles / 12 moles = 2.5 atm / Total pressure
Total pressure = 2.5 atm / (3mol/12mol)
Total pressure = 10 atm