J.R. S. answered 01/15/24
Ph.D. University Professor with 10+ years Tutoring Experience
moles IBr present = 7.78x10-1 g x 1 mol IBr / 207 g = 3.76x10-3 mol
moles F2 present = 1.53x10-1 g x 1 mol F2 / 38.0 g = 4.03x10-3mol
F2 is limiting as it takes 4x as much as IBr, and there isn't 4x as much. All the F2 will be used up.
Using an ICE table to see what happens, we have...
IBr (g) + 4F2 (g) ===> IF5 (g) + BrF3 (g)
3.76x10-3.......4.03x10-3...........0....................0...............Initial
1.01x10-3......-4.03x10-3........+1.01x10-3...+1.01x10-3....Change
2.75x10-3............0...................1.01x10-3.....1.01x10-3....Equilibrium
Moles of IF5 @ equilibrium = 1.01x10-3 and pressure can be determined using the ideal gas law:
PV = nRT
P = pressure = ?
V = volume = 9.90 L
n = moles IF5 = 1.01x10-3
R = gas constant = 0.0821 Latm/Kmol
T = temperature in K = 495K
Solving for P, we have...
P = nRT/V = (1.01x10-3)(0.0821)(495) / 9.90
P = 4.15x10-3 atm (3 sig figs)