Question

The solid rocket boosters for the space shuttle employ a mixture of aluminum and ammonium perchlorate (molar mass = 117 g/mol) as fuel. The balanced equation is 3Al(s) + 3NH4ClO4(s) Al2O3(s) + AlCl3(s) + 3NO(g) + 6H2O(g). How many liters of gas measured at STP are produced from 235 g of NH4ClO4 with excess aluminum?

Answer 1

Answer : The volume of gas at STP produced are 45.0 L

Explanation :

First we have to calculate the moles of ammonium perchlorate.

$\text{Moles of }NH_4ClO_4=\frac{\text{Mass of }NH_4ClO_4}{\text{Molar mass of }NH_4ClO_4}$

Molar mass of $NH_4ClO_4$ = 117 g/mole

$\text{Moles of }NH_4ClO_4=\frac{235g}{117g/mole}=2.01mole$

Now we have to calculate the moles of $NO$ gas produced during the reaction.

The balanced chemical reaction is,

$3Al(s)+3NH_4ClO_4(s)\rightarrow Al_2O_3(s)+AlCl_3(s)+3NO(g)+6H_2O(g)$

From the reaction we conclude that,

As, 3 moles of $NH_4ClO_4$ produces 3 moles of NO gas

So, 2.01 moles of $NH_4ClO_4$ produces 2.01 moles of NO gas

Now we have to calculate the volume of gas at STP.

At STP, 1 mole of substance occupy 22.4 L volume of gas.

As, 1 mole of NO gas occupy 22.4 L volume of gas.

So, 2.01 mole of NO gas occupy 2.01 × 22.4 L = 45.0 L volume of gas.

Therefore, the volume of gas at STP produced are 45.0 L