Question

During the thermal decomposition of copper carbonate (CuCO₃), a student noticed the mass of the copper oxide formed was less than the mass of the copper carbonate at the start of the experiment. How does this reaction still follow the law of conservation of mass?

A) The reaction is incomplete, and some of the copper carbonate remains unreacted.
B) Some of the gases produced during the decomposition escape from the reaction vessel.
C) The student measured incorrectly, leading to inaccurate results.
D) Copper oxide has a lower density compared to copper carbonate, causing a decrease in mass.

Answer 1

The observation that the mass of the copper oxide formed during the thermal decomposition of copper carbonate is less than the mass of the copper carbonate at the start of the experiment is in accordance with the law of conservation of mass.

Step-by-step explanation:

The observation that the mass of the copper oxide formed during the thermal decomposition of copper carbonate is less than the mass of the copper carbonate at the start of the experiment is still in accordance with the law of conservation of mass. This is because the loss in mass can be attributed to one of the following reasons:

1. The reaction is incomplete, and some of the copper carbonate remains unreacted.
2. Some of the gases produced during the decomposition escape from the reaction vessel.
3. The student measured incorrectly, leading to inaccurate results.
4. Copper oxide has a lower density compared to copper carbonate, causing a decrease in mass.

Any of these reasons show that the law of conservation of mass still holds true for this reaction.