Question

According to the reaction, below, how many grams of aluminum are needed to react fully with 100 grams of sulfur? 2AL + 3s - Al2S3

Answer 1

Answer: 56.2 g of Aluminium is needed to react fully with 100 grams of sulphur.

Explanation:

To calculate the moles :

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

$\text{Moles of} S=\frac{100g}{32g/mol}=3.125moles$

The balanced chemical equation is:

$2Al+3S\rightarrow Al_2S_3$  

According to stoichiometry :

3 moles of $S$ require = 2 moles of $Al$

Thus 3.125 moles of $S$ will require=$\frac{2}{3}\times 3.125=2.08moles$  of $Al$  

Mass of $Al=moles\times {\text {Molar mass}}=2.08moles\times 27g/mol=56.2g$

Thus 56.2 g of Aluminium is needed to react fully with 100 grams of sulphur.