Question

Hydrogen gas can be produced by the reaction of magnesium metal with hydrochloric acid. Identify the limiting reagent when 6.00g of HCl reacts with 5.00g of Mg?

Answer 1

In the reaction between 6.00g of HCl and 5.00g of Mg to produce hydrogen gas, hydrochloric acid (HCl) is the limiting reagent due to having fewer moles available compared to magnesium (Mg), which is present in excess.

Step-by-step explanation:

The question concerns the identification of the limiting reagent when 6.00g of HCl reacts with 5.00g of Mg. To find which reagent is limiting, we must compare the moles of each reactant based on the balanced chemical equation: Mg(s) + 2 HCl(aq) → MgCl₂(aq) + H₂(g).

First, calculate the moles of HCl and Mg:

• HCl has a molar mass of approximately 36.46 g/mol, so 6.00 g of HCl is 6.00/36.46 = 0.1647 moles of HCl.
• Mg has a molar mass of approximately 24.31 g/mol, so 5.00 g of Mg is 5.00/24.31 = 0.2057 moles of Mg.

The balanced equation shows that 1 mol of Mg reacts with 2 mol of HCl. Since we have 0.2057 moles of Mg, we would need 0.2057 × 2 = 0.4114 moles of HCl. However, we have only 0.1647 moles of HCl available.

As a result, hydrochloric acid (HCl) is the limiting reagent because there are not enough moles of HCl to react with the available moles of Mg. The Mg would be the excess reagent.