using the equation you wrote determine how many moles of butane c4h10 are needed to react with 5.5 moles of oxygen

0.846 moles.

Explanation:

This is a stichiometric problem. The balanced equation of complete combustion of butane is:

C₄H₁₀ + 6.5 O₂ → 4 CO₂ + 5 H₂O

It is clear from the stichiometry of the balanced equation that complete combustion of 1.0 mole of butane needs 6.5 moles of O₂ to produce 4 moles of CO₂ and 5 moles of H₂O.

Using cross multiplication:

1.0 mole of C₄H₁₀ reacts with → 6.5 moles of O₂? moles of C₄H₁₀ are needed to react with → 5.5 moles of O₂ The number of moles of C₄H₁₀ that are needed to react with 5.5 moles of O₂ = (1.0 x 5.5 moles of O₂) / (6.5 moles of O₂) = 0.846 moles.