The Law of Conservation of Mass (Day 2)

Today we continued our investigation of the Law of Conservation of Mass, but this time we used the classic “baking soda and vinegar” reaction. When baking soda mixes with vinegar, it causes a chemical reaction which produces sodium acetate, water, and carbon dioxide. The observable clues are that it bubbles and also turns cold.

Students carefully measured the mass of the baking soda and vinegar before and after the reaction. And, much tot heir surprise, the mass decreased. So were we breaking the law? We wondered. Students then repeated the experiment a second time, but this time they covered the reaction with a balloon.

By trapping the CO2 that the reaction created, we were able to prove that mass was, in fact, conserved. The reason we saw a mass decrease during our first test was that the carbon dioxide escaped. When covered with a balloon, however, the masses before and after were about the same. No going to jail today either 😉

November 25 – LoCoM Lab – Baking Soda & Vinegar (pg315)

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