The equation shows the reaction between zinc metal and hydrochloric acid.

Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)

What is the theoretical yield of hydrogen gas if 5.00 mol of zinc are added to an excess of hydrochloric acid?

The proper reaction equation is expressed below:

Zn + HCl → ZnCl₂ + H₂

Given parameters:

Number of moles of Zn = 5mol

Unknown:

Theoretical yield of H₂

Solution:

The theoretical yield determines the amount of a product produced in a reaction. In a reaction, some reactants in short supply gives a general view to the amount of products that will be formed and are called limiting reagents.

We know that the limiting reagent here is Zn. From here we can estimate the amount of H₂ produced.

To find the amount of hydrogen gas,

we know that from the balanced reaction equation:

1 mole of Zn produced 1 mole of H₂;

Now, 5 mole of Zn will produce 5 mole of H₂

To find the mass of H₂ produced, we use the expression below:

mass of H₂ = number of moles of H₂ x molar mass of H₂

Molar mass of H₂ = 2g/mol

mass of H₂ = 5 x 2 = 10g

Theoretical yield of H₂ is 10g