Decaborane, B 10 H 14 , was used as a fuel for rockets in the 1950\'s . It ignit

Question

Decaborane, B10H14, was used as a fuel for rockets in the 1950's . It ignites spontaneously with O2 according to the following reaction:
B10H14 + 11O2 5B2O3 + 7H2O

a. If a rocket's fuel tanks contain 4.255E+5g of decaborane and 7.351E+5g of oxygen, which of the reactants is the limiting reagent?

b. What mass of the other reactant is left over after the limiting reagent in the above mixture has been completely consumed?

c. The best design for rockets is one in which both fuel materials run out at the same time to minimize excess mass. If the total mass of both components in a decaborane/oxygen rocket must be 1.955E+6g, what mass of liquid oxygen should be used?

Explanation / Answer

a. moles of B10H14 = g/molar mass

= 4.255 x 10^5/122.22

= 3481.43 mols

moles of O2 = 7.351 x 10^5/32

= 22972 mols

If of all B10H14 is used up we would need = 11 x 3481.43 = 38295.73 mols of O2

Since only 22972 mols of O2 is available, this is the limiting reagent

If all of O2 is used up we would need = 1/11 x 22972 = 2088.36 mols of B10H14

b. After complete reaction,

moles of B10H14 left = 3481.43 - 2088.36

= 1393.07 mols

mass of B10H14 left = 1.70 x 10^5 g

c. With total mass of B10H14 + O2 = 1.955 x 10^6 g

mass of B10H14 = (1/122.22) x 11 x 1.955 x 10^6 = 1.76 x 10^5 g

mass of O2 = 1.955 x 10^6 - 1.76 x 10^5 = 1.78 x 10^6 g

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.