Question

if 5.0g zinc reacts with 10.0 g hci to produce h2 gas and znci2 according to the following equation zn=2hci znci2 + h2 what is the limiting reactant and how many grams of h2 will be produced

Answer 1

Answer: The mass of $H_2$ produced is 0.153 g

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

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

• For zinc:

Given mass of zinc = 5.0 g

Molar mass of zinc = 65.38 g/mol

Putting values in equation 1, we get:

$\text{Moles of zinc}=\frac{5.0g}{65.38g/mol}=0.0765mol$

• For HCl:

Given mass of HCl = 10.0 g

Molar mass of HCl = 36.46 g/mol

Putting values in equation 1, we get:

$\text{Moles of HCl}=\frac{10.0g}{36.46g/mol}=0.274mol$

The given chemical equation follows:

$Zn+2HCl\rightarrow ZnCl_2+H_2$

By stoichiometry of the reaction:

If 1 mole of zinc reacts with 2 moles of HCl

So, 0.0765 moles of zinc will react with = $\frac{2}{1}\times 0.0765=0.153mol$ of HCl

As the given amount of HCl is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.

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

By the stoichiometry of the reaction:

If 1 mole of zinc produces 1 mole of $H_2$

So, 0.0765 moles of zinc will produce = $\frac{1}{1}\times 0.0765=0.0765mol$ of $H_2$

We know, molar mass of $H_2$ = 2 g/mol

Putting values in above equation, we get:

$\text{Mass of }H_2=(0.0765mol\times 2g/mol)=0.153g$

Hence, the mass of $H_2$ produced is 0.153 g