Question

balance this equation: mg + hcl → mgcl₂ + h₂
mg + 2hcl → mgcl₂ + h₂
2mg + hcl → 2mgcl₂ + h₂
mg + hcl → mgcl₂ + 2h₂
mg + 2hcl → mgcl₂ + 2h₂
in the reaction zn + cuso₄ → znso₄ + cu, what is happening to the copper?
the copper is joining with the sulfate.
the copper is being replaced by the zinc.
the copper is staying the same.
the copper is disappearing.
look at this equation: h₂ + o₂ → h₂o. is it balanced?
yes, because there are the same number of molecules on both sides.
no, because there are more hydrogen atoms on the left.
no, because there are more oxygen atoms on the left.
yes, because hydrogen and oxygen are on both sides.

Explanation:

Step1: Analyze Mg + HCl → MgCl₂ + H₂

Count atoms on both sides. On left: 1 Mg, 1 H, 1 Cl. On right: 1 Mg, 2 Cl, 2 H. To balance Cl and H, put 2 in front of HCl. So balanced equation is Mg + 2HCl → MgCl₂ + H₂.

Step2: Analyze Zn + CuSO₄ → ZnSO₄ + Cu

This is a single - displacement reaction. Zinc is more reactive than copper. Zinc replaces copper in copper sulfate. So copper is being replaced by zinc.

Step3: Analyze H₂ + O₂ → H₂O

On left: 2 H, 2 O. On right: 2 H, 1 O. There are more oxygen atoms on the left. So it is not balanced.

Answer:

1. Mg + 2HCl → MgCl₂ + H₂
2. The copper is being replaced by the zinc.
3. No, because there are more oxygen atoms on the left.