Conservation of Mass

What is the definition of chemical reaction?

• The input which reacts chemically to create product
• a system where none of the reactants or products are allowed to escape
• occurs when the atoms and molecules of two or more substances rearrange to form new substances
• the output, or result of a chemical reaction

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit
• Invisible
• Transformed, changed
• None of the above

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NGSS.MS-PS1-5

Which of these is NOT a chemical reaction?

• Two liquids mix to give a new color
• Two gases react to make a liquid
• A liquid and a solid mix to make a gas
• Melting an aluminum can 

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NGSS.MS-PS1-2

Substance made up of chemically combined elements

• atom
• element
• electron
• compound

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NGSS.MS-PS1-1

Substance that cannot be broken into simpler substances

• element
• molecule
• gram
• proton

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NGSS.HS-PS1-1

Anything that has mass & takes up space

• gravity
• force
• matter
• volume

Suppose a reaction were to happen in an open container in a lab.  During the reaction, the scientist observes the chemicals bubble, and produce a gas.   During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g.  Explain what happened.  

• His chemical reaction defied the law of conservation of mass
• The product destroyed mass during the reaction
• The reactants created matter during the reaction
• The gas that was produced was not able to be weighed since the container was open.  

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NGSS.MS-PS1-2

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What will weigh more when a chemical change is complete?  The reactants before the chemical reaction, or the product after the reaction is complete?

• They both will weigh the same
• The product always weighs more than the reactant
• The reactant will weigh more than the product
• They both will loose mass after the reaction

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NGSS.MS-PS1-2

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-PS1-2

NGSS.MS-PS1-5

Evidence of a chemical reaction include:

• Phase change
• No new substance
• Bubbles forming
• Shape change

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NGSS.MS-PS1-2