Intro to Conservation Of Mass

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Question 1: In science, does the word “matter” refer to thoughts?

• No

• Yes

Answer explanation

No. In science we use it to refer to physical things (‘stuff’) that take up space and have mass.

Can we measure something’s “mass” in Celsius?

• No

• Yes

Answer explanation

No. Mass is similar to weight but we measure it with a balance and the units are in grams or kilograms.

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Is sawing wood an example of a physical change

• No

• Yes

Answer explanation

Yes. Our muscles or power tools change matter physically. 

Is the mass of a closed system different before and after a physical change?

• No

• Yes

Answer explanation

No. They are the same. The examples we showed are solids (clay) and liquids.

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Is the mass of a closed system the same before and after matter goes from the solid to a liquid state?

• No

• Yes

Answer explanation

Yes. Mass is conserved (which means it stays the same) in a closed system when matter changes states.

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Does matter no longer exist when it changes from a liquid to a gas state, such as boiling water?

• No

• Yes

Answer explanation

No. It’s often invisible to us, but we can capture it.

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During a chemical reaction, is mass destroyed such that it no longer exists?

• No

• Yes

Answer explanation

No. The mass of a closed system is the same before and after a chemical reaction. Mass is not destroyed in a chemical reaction.

Tags

NGSS.MS-PS1-5

Are fireworks or a campfire an example of a chemical reaction?

• No

• Yes

Answer explanation

Yes. Fires are a type of chemical reaction called combustion.

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