Question

Which of the following equations violates the law of conservation of mass?

A. FeCl3 + 3NaOH yields Fe(OH)3 + 3NaCl

B. CS2 + 3O2 yields CO2 + 2SO2

C. Mg(ClO3)2 yields MgCl2 + 2O2

D. Zn + H2SO4 yields H2 + ZnSO4

Answer 1

Hi!

The chemical equation that violates the law of conservation of mass is C

Mg(ClO₃)₂ → MgCl₂ + 2O₂

Let's see why:

The number of atoms from each element should be the same on both sides of the equation.

For Mg:1 atoms Left Side=1 atoms Right Side
For Cl:2 atoms Left Side=2 atoms Right Side
For O: 6 atoms Left Side ≠ 4 atoms Right Side

So, the equation is not balanced for O. The correct balanced equation is the following:

Mg(ClO₃)₂ → MgCl₂ + 3O₂

Have a nice day!