Question

How does the law of conservation of mass apply to this reaction Mg+HCL->H2+MgCl2?

Answer 1

Answer :

Law of conservation of mass : It states that the mass of reactant molecules must be equal to the mass of product molecules.

• The given unbalanced reaction is,

$Mg+HCl\rightarrow H_2+MgCl_2$

First we have to balance the chemical reaction.

• The balanced chemical reaction is,

$Mg+2HCl\rightarrow H_2+MgCl_2$

Now we have  to calculate the mass of reactant side molecules and product side molecules.

Mass of reactants = $Mg+2HCl=(24)+2(1+35.5)=97g$

Mass of products = $H_2+MgCl_2=2(1)+(24+2(35.5))=97g$

From this we conclude that the mass of reactant is equal to the mass of product.

Answer 2

Answer:

Law of conservation of mass do not apply to this equation.

Explanation:

The law of conservation of mass states that the mass of objects/element before any reaction must be equal to the mass of objects/element after the reaction.  

Here in this case –  

Mg+HCL->H2+MgCl2

Mass of Mg before reaction = 1

Mass of H before reaction = 1

Mass of Cl before reaction = 1

Mass of Mg after reaction = 1

Mass of H after reaction = 2

Mass of Cl after reaction = 2

Thus it is clear that mass of H and Cl before and after the reaction is not equal and thus law of conservation of mass do not apply to this equation.