How many moles of hydrogen are produced from the reaction of 3.5 moles of zinc with excess
hydrochloric acid (HCI)?

The answer to your question is 3.5 moles of H₂

Explanation:

Data

moles of H₂ = ?

moles of Zn = 3.5 moles

moles of HCl = excess

Process

1.- Write the balanced chemical reaction

             Zn  +  2HCl  ⇒   ZnCl₂  +  H₂

  Reactants         Elements     Products

           1                     Zn                  1

           2                    Cl                   2

           2                    H                    2

2.- Use the coefficients of the balanced reaction to calculate the moles of H₂

               1 mol of Zn 1 mol of H₂

             3.5 moles of Zn  x

                              x = (3.5 x 1)/1

                              x = 3.5 moles of H₂