GCSE Chemistry - Conservation of Mass #26

The video explains the principle of conservation of mass in chemical reactions, emphasizing that mass is conserved as atoms are neither created nor destroyed. It illustrates this with examples, showing how to balance equations by comparing relative formula masses. The video also discusses exceptions when gases are involved, which can lead to perceived changes in mass. It highlights the importance of conducting experiments in sealed containers to ensure accurate mass measurements, as gases can escape or enter from the air, affecting the results.

What does the conservation of mass principle state about atoms in a chemical reaction?

• Atoms are only created.

• Atoms are rearranged but not created or destroyed.

• Atoms are created and destroyed.

• Atoms are only destroyed.

In the reaction between sodium and chlorine, why must there be two sodium chlorides formed?

• Because each chlorine molecule contains two chlorine atoms.

• Because sodium is heavier than chlorine.

• Because chlorine is a gas.

• Because sodium is more reactive.

How can we demonstrate the conservation of mass using relative formula masses?

• By ensuring the total mass of reactants equals the total mass of products.

• By comparing the number of molecules on each side.

• By counting the number of atoms on each side.

• By measuring the volume of gases produced.

Why might the mass appear to increase in a reaction involving a gas?

• Because the gas comes from the air and is not initially measured.

• Because the gas is absorbed by the solid reactants.

• Because the gas is lighter than the solid reactants.

• Because the gas is heavier than the solid reactants.

What happens to the mass of products when a reaction is conducted in a sealed container?

• The mass of products is unpredictable.

• The mass of products is less than the reactants.

• The mass of products is more than the reactants.

• The mass of products equals the mass of reactants.