NGSS.MS-PS1-5

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction
• Mass is created in a physical change
• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
• Mass is never created or destroyed

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NGSS.MS-PS1-5

Students react baking soda & vinegar.
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?

• The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.
• Bubbles were produced during the reaction, which meant that a gas was being produced.
• The plastic bag did not change in any way, indicating that it was not involved in the reaction.
• The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

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NGSS.MS-PS1-5

The Law of Conservation of Matter

• tells how many atoms of an element are contained in one molecule or formula unit.

• the starting materials in a chemical reaction

• the new substances that are formed in a chemical reaction

• A law stating that atoms are not created or destroyed during a chemical reaction.

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NGSS.MS-PS1-5

The law of conservation of mass can be demonstrated by a chemical reaction. Which of the following models of a chemical reaction best represents the law of conservation of mass?

• 
• 
• 
• 

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NGSS.MS-PS1-5

chemical reaction

• a process in which atoms rearrange to form new substances
• a set of interacting parts forming a complex whole
• a proposed answer to a question about the natural world
• a claim supported by evidence

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NGSS.MS-PS1-5

During a chemical reaction, atoms are ___________.

• left alone
• left in the original molecules
• completely destroyed
• rearranged

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NGSS.MS-PS1-5

So, the Law of Conservation of Mass would tell us that the mass of all the REACTANTS must __________ the mass of all PRODUCTS in a chemical reaction.

• equal

• be greater than

• be less than

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NGSS.MS-PS1-5

Is this balanced?...
Al + O₂ --> 2Al₂O₃

• Yes!
• NO!

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NGSS.MS-PS1-5

The law of conservation of mass tells us that matter

• cannot be created or destroyed

• can be created and destroyed

• Can be destroyed

• Can be created

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NGSS.MS-PS1-5

The Law of Conservation of Mass States

• Energy cannot be created nor destroyed, it can only change form.

• Mass cannot be created nor destroyed, it can only change form.

• Mass can be created or destroyed, it cannot change form.

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NGSS.MS-PS1-5