Question

how does the law of conservation of mass apply to this reaction mg + 2hcl → h₂ + mgcl₂?
○ hydrogen and chlorine need to be balanced. there is an equal amount of magnesium on each side
○ the equation needs to be balanced. there are fewer hydrogen atoms in the equation than magnesium or chlorine.
○ only the hydrogen needs to be balanced. there are equal numbers of magnesium and chlorine.
○ the law of conservation of mass has already been applied. there is an equal number of each element on both sides of the equation.

Explanation:

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. In the given reaction \(Mg + 2HCl \to H_2+MgCl_2\), we check the number of atoms of each element on both sides.

• Magnesium (\(Mg\)): 1 atom on the left (\(Mg\)) and 1 atom on the right (\(MgCl_2\)).
• Hydrogen (\(H\)): 2 atoms on the left (\(2HCl\)) and 2 atoms on the right (\(H_2\)).
• Chlorine (\(Cl\)): 2 atoms on the left (\(2HCl\)) and 2 atoms on the right (\(MgCl_2\)).

Since the number of atoms of each element (\(Mg\), \(H\), and \(Cl\)) is the same on both sides of the equation, the law of conservation of mass has already been applied.

Answer:

The law of conservation of mass has already been applied. There is an equal number of each element on both sides of the equation.