Answer to Question #24952 in Chemistry for jordan

Question

At STP, how many grams of butane would be needed to react with 1178.0 mL of oxygen gas?

Answer 1

The chemical equation for the burning reaction is
2C₄H₁₀ + 13O₂ = 8CO₂ + 10H₂O
According to the ideal gas law
pV = nRT
n = pV/RT
STP:
p = 1 atm
V = 22.4 L
T = 273 K
R = 0.082 atm x L/ (mol x K)

n(O₂) = pV/RT = (1 x 1.178) / (0.082 x 273) = 0.053 mol

According to chemical equation:
n(C₄H₁₀) = n(O₂) x 2 / 13 = 0.053 x 2 / 13 = 8.15x 10^-3 mol
m(C₄H₁₀) = n(C₄H₁₀) x M_W(C₄H₁₀) = n(C₄H₁₀) x (4 xM_W(C) + 10 xM_W(H)) = 8.15 x 10^-3 x (4 x 12 + 10 x 1) = 0.473g

Answer : m(C₄H₁₀) = 0.473g