If a 1250 g sample of B4H10 burns completely in O2 what will

If a 1.250 g sample of B4H10 burns completely in O2, what will be the pressure of the gasesous water in a 4.25 L flask at 30.0 degrees celcius.

Given this equation: 2 B4H10 (g) + 11 O2(g) = 4 B2O3(s) + 10 H20(g)

Solution

Calculate the moles of B4H10 present in 0.050 g. (1.250g / 53.3 g/mol = .023mol)

Multiply the mole of B4H10 by 5 to get n (moles of H2O = 5x.023 = .115mol)

PV=nRT

P (atm) = 0.115 x 0.082057 x (273+30) / 4.25 L

P = 0.672 atm