The Fizzing Tablet
Leo drops a fizzing tablet into an open jar of water on a scale. As the bubbles pop, the reading drops from 100 g to 91 g.
Did the fizzing destroy some matter?
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Science · Grade 5 Science
Chapter 1: Matter and Its Properties
The number refuses to move.
Leo drops a fizzing tablet into an open jar of water on a scale. As the bubbles pop, the reading drops from 100 g to 91 g.
Did the fizzing destroy some matter?
Make your guess to turn the page.
Still to come: 8 pages · Words to Know · What We Learned · 4 questions · Explain It in Writing · Ask and Wonder
The idea this lesson is working on — Children think a gas weighs nothing, so making one must lose mass — and an open jar seems to prove them right. The story starts from that very result and changes only the lid: sealed, the same fizz leaves the scale on 100 g. Ask: if the fizz destroyed 9 g, why did it destroy nothing with the lid on? The answer to reach is that the gas has mass and left.
Why the container must be sealed — Burning wood in the open seems to lose mass because gases escape into the air. Seal it, and the mass holds. Apparent losses are almost always something leaving that nobody weighed — which is why, when a reading drops, the question to ask is what got out.
About the numbers — Real fizzing tablets give off well under a gram of gas each, so 9 g stands for a large handful of them; the chapter keeps 100 g and 91 g so the subtraction is easy to see. If you try it at home, use a plastic bottle with a balloon over the neck rather than a screwed-down jar, and weigh to a tenth of a gram if you can.