When 125g zinc carbonate is heated, 81g zinc oxide is produced. Calculate the mass of carbon dioxide produced.
Mass of carbon dioxide=___g

Mass of carbon dioxide= 44 g

Explanation:

Zinc carbonate      →   Zinc oxide + carbon dioxide

  125 g                  =       81 g  + X

X = 125 g-81 g

X = 44 g

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

In given photosynthesis reaction:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.