The compound diborane was at one time considered for use as a rocket
fuel. How many grams of liquid oxygen would a rocket have to carry to
burn 14 kilograms (14,000 g) of diborane completely? *
B2H(g) + 3 O2(g) → B2O3(s) + 3 H2O(g)

34,690 g O₂ used.

Explanation:

Balance Equation

              12B₂H             +                      21O₂                           => 12B₂O₃ + 6H₂O

Given 14,000g B₂H          moles O₂ consumed to burn 619.47 mol B₂H

=(14,000g/22.6g/mol)        = 21/12 x 619.47 mole O₂ = 1084 mole O₂

= 619.47 mol B₂H used        1084 mol O₂ x 32 g/mol = 34,690 g O₂ used.