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A student performs a reaction between hydrochloric acid (HCI) and sodium bicarbonate (NaHCOs) in a sealed container. The balanced chemical equation for the reaction is:

HCI (aq)+NaHCOs (s)-NaCI (aq)+H2O (I)+CO2 (g)
Before the reaction, the total mass of the sealed container and its contents is measured to be 120.0 grams. After the reaction is complete, the student notices bubbling inside the container (gas formation), but the
container remains sealed. The total mass is measured again and is still 120.0 grams.

What does this result demonstrate about the law of conservation of mass?

(1 point)

Mass was lost during the reaction because a gas was produced.

O Mass was gained during the reaction because water was formed.

Mass was conserved because the sealed system prevented gas from escaping.

Mass changed because chemical reactions always absorb or release energy.

All Answers 1

Answered by GPT-5 mini AI
Correct answer: Mass was conserved because the sealed system prevented gas from escaping.

Explanation: The law of conservation of mass states mass is neither created nor destroyed in a chemical reaction. Although CO2 gas formed (bubbling), because the container was sealed none of the gas escaped, so the total mass before and after remained the same.