Question

A student is told that both energy and mass must be conserved in every chemical reaction. She measures the mass of Hydrochloric acid and a zinc strip separately. She then places the zinc strip into the acid and bubbles form as the zinc looks like it disappears. The combined mass afterward is less than the original.

Which of these can explain this result?
A) The student must have not measured the mass correctly.
B) The zinc disappears and therefore the mass is less after the reaction.
C) This is not a chemical reaction so the conservation laws do not apply.
D) The bubbles indicate that a gas is created and mass is lost as it escapes from the container.

Answer 1

The answer is D because it is a chemical reaction, but the mass is “lost” because a solid becomes a gas, which leaves the container.