A student combines two liquids in a beaker. She observes that the mass of the combined liquid is less than the mass of the two separate liquids. The student claims that this observation shows that matter is not conserved in chemical reactions. Which statement explains why the student’s claim is incorrect?(1 point)

Question

Responses

The reaction did not change the physical properties of the liquids.
The reaction did not change the physical properties of the liquids.

The combined liquid was warmer than the two separate liquids.
The combined liquid was warmer than the two separate liquids.

The reaction produced a gas that escaped the beaker.
The reaction produced a gas that escaped the beaker.

The product contained fewer atoms than the reactants.

Answer 1

The correct statement that explains why the student’s claim is incorrect is:

The reaction produced a gas that escaped the beaker.

This explains that the mass appeared to decrease because some of the matter (in the form of gas) was lost from the system, which does not violate the law of conservation of mass. In a closed system, matter is conserved, but in this case, the system was not closed, leading to the observed loss in mass.