Final answer:
To balance the chemical equation Zn(s) + HCl(aq) → ZnCl₂(aq) + H₂(g), a coefficient of 2 should be placed in front of HCl to ensure there are equal numbers of chlorine atoms on both sides, resulting in the balanced equation: Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g).
Step-by-step explanation:
The question is asking how to balance the chemical equation when solid zinc metal reacts with aqueous hydrochloric acid to form an aqueous solution of zinc chloride and hydrogen gas. To balance this equation, we need to ensure that there is an equal number of each type of atom on both sides of the reaction.
The unbalanced chemical equation is:
Zn(s) + HCl(aq) → ZnCl2(aq) + H2(g)
We can see that there are 2 chlorine atoms in ZnCl2 on the product side but only 1 chlorine atom in HCl on the reactant side. Therefore, we need to add a coefficient of 2 in front of HCl to balance the chlorine atoms:
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Now, the zinc, chlorine, and hydrogen atoms are balanced. The balanced equation shows the oxidation of zinc and the reduction of hydrogen ions to produce zinc chloride (ZnCl2) in the aqueous phase and hydrogen gas (H2).
The balanced chemical equation is:
Zn(s) + 2HCl(aq) → ZnCl2 (aq) + H2(g)