Question

A student carries out the following reaction in the laboratory:

Sodium carbonate + Copper sulphate $\to$ Copper carbonate + Sodium sulphate

How could you determine the reaction obeyed the law of conservation of mass?

• A. Mass of the sample after the reaction is compared to the mass before the reaction begins
• B. Mass of the sample as the reaction is run is measured
• C. Filtering the reactants
• D. Running the reaction in an open system

Answer 1

Answer: (A)

Mass of the sample after the reaction is compared to the mass before the reaction begins

Law of conservation of mass states that mass of the reactants before the reaction should be same as the mass of the products after the reaction.

We will measure the mass of the product and see if it is the same as the mass of the reactants. Both will be same, thus showing the law of conservation of mass is obeyed.

$\Rightarrow$ Mass of the reactants = Mass of the products after the reaction