Mass of NH4ClO4 for every kilogram of Al...?

Question

The reusable booster rockets of the space shuttle use a mixture of aluminum and ammonium perchlorate as fuel. A possible reaction is given below.

3 Al(s) + 3 NH4ClO4(s) Al2O3(s) + AlCl3(s) + 3 NO(g) + 6 H2O(g)

What mass of NH4ClO4 should be used in the fuel mixture for every kilogram of Al?

I've been stuck on this problem for a while... Any help is greatly appreciated! Thanks in advance.

Answer 1

I believe the equation is

3 Al(s) + 3 NH4ClO4(s) ---->Al2O3(s) + AlCl3(s) + 3 NO(g) + 6 H2O(g

so we count up all the Al on the left side of the equation

Al =3

Molar mass Al =26.9815386 g·mol−1

so 3Al in the equation to 3 NH4ClO4

1 kg Al = 1000g Al

1000g/26.9815386 = 37.06 moles of Al in 1 kg

the molar ratio is 3 Al to 3 NH4ClO4 for the reaction

so there is one mole of Al for each mole of NH4ClO4 required for the reaction

37.06 moles Al=37.06 moles of NH4ClO4

The molar mass of NH4ClO4 is 117.48876 g/mol

So 37.06*117.48876 = 4354.133

divide by 1000 to get kg   4354.133/1000=4.354 kg NH4ClO4

Answer 2

The atomic weight of 3Al is 26.982 * 3 = 80.946 and the atomic weight of 3 NH4ClO4 is 117.489 * 3 = 352.467

so for every 80.946 gm of Al you need 352.467 gm of NH4ClO4 and by ratio  for every kg of Al you need 352.467/80.946 = 4.354 kg of NH4ClO4