Question

The drain cleaner Drano contains small bits of aluminum which react with NaOH (Drano's main ingredient) to produce bubbles of hydrogen gas which may facilitate the cleaner's "action." How many moles of H2 are produced when 0.150 g of Al react with plenty of NaOH

Answer 1

Answer: 0.00825 moles of hydrogen are produced.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$      .....(1)

For aluminium:

Given mass of aluminium = 0.150 g

Molar mass of aluminium = 27 g/mol

Putting values in equation 1, we get:

$\text{Moles of aluminium}=\frac{0.150g}{27g/mol}=0.0055mol$

The chemical equation for the reaction of aluminium and NaOH follows:

$2Al+2NaOH+6H_2O\rightarrow 2NaAl(OH)_4+3H_2$

As, given amount of NaOH is in plenty. So, it is considered as an excess reagent.

Thus, aluminium is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

2 moles of aluminium produces = 3 moles of hydrogen

So, 0.0055 moles of aluminium will produce = $\frac{3}{2}\times 0.0055=0.00825mol$ moles of hydrogen