Question

Josh is measuring the enthalpy change associated with the reaction of Mg metal with aqueous hydrochloric acid. He adds 0.343 g of Mg ribbon to 93.91 mL of 1.00 M aqueous HCl solution. Determine first the limiting reagent, and answer the number of moles of limiting reagent that will react, assuming the reaction proceeds to completion

Answer 1

The reaction of Mg metal with aqueous hydrochloric acid is represented by the following equation.

0.343 g of Mg ribbon (molar mass 24.3 g/mol) corresponds to

93.91 mL of 1.00 M aqueous HCl solution corresponds to

0.0141 moles of Mg will react with moles of HCl, however 0.09391 moles of HCl are present. Hence, HCl is the excess reagent and Mg is the limiting reagent.

The number of moles of limiting reagent that will react, (assuming the reaction proceeds to completion) are 0.0141 moles.