Law of Conservation of Mass

Law of Conservation of Mass

​Clear Learning Target:

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I can define the Law of Conservation of Mass so that I can determine if examples given follow the rule.

​Elements and Compounds

https://www.youtube.com/watch?v=i2OE9ljBKD8

​Physical Change

• A Physical Change happens when a substance ​changes but no new substance is formed.

• ​Physical Change occurs when the state of a substance changes.

• Freezing

• Evaporating

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​Examples include: Water Freezing, Cutting Paper, Melting Butter, Breaking Glass

​Chemical Change

​A Chemical Change Occurs when a new substance is formed.

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​Indications that a new substance has formed (Chemical Change):

• A change in color

• Formation of Bubbles

• ​Temperature changes

• ​Forms a gas

​Examples of a Chemical Change: Wood burning, A nail rusting, Food Rotting.

Multiple Choice

Is this an example of a Physical or Chemical change? 

• Physical

• Chemical

Multiple Choice

Is this a image a physical or chemical change?

• Physical 

• Chemical

Multiple Choice

Is this image a physical or chemical change? 

• Physical 

• Chemical

​Closed System Vs. Open System

​Open System- Allows matter and energy to flow in and out freely.

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Ex. Baking bread in an oven, Melting ice in a pan

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​Closed System- matter or energy is unable to go in or out.

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​Ex. A cup of coffee with a lid on it, Cooking dinner in a pressure cooker

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Fill in the Blanks

Closed or Open System? An example of a _____ _____ is hot chocolate in a thermos with a lid

​Law of Conservation of Mass

​Antoine Lavoisier - "Revolutionized Chemistry"

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• ​Lavoisier discovered that "Mass can not be created or destroyed" by carefully measuring the product and reactants in many of the chemical reactions he was researching.

• ​Law of Conservation of Mass states that: "Mass can not be created or destroyed"

Products vs. Reactants

​RAP = Reactants Arrow Products

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​Products and Reactants in a Chemical Equation

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​Products and Reactants in a Chemical Reaction

​Reaction between Methane and Oxygen :

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​All of the atoms that were present at the beginning of the reaction (reactants) are still present in the products. They have just been moved around or transformed!

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Multiple Choice

What does the Law of Conservation of Mass state?

• Mass is created at the end of a chemical reaction

• Mass can not be created or destoryed 

• Mass is created in a physical change 

• New chemicals are formed when a chemical reaction takes place.

Counting The Atoms: Subscripts Vs. Coefficients

Multiple Choice

Using the picture, what is the coefficient of this chemical compound? 

• 3

• 4

• There isn't one 

Multiple Choice

Using the picture, what is the subscript of this chemical compound? 

• 4

• 3

• There isn't one

Multiple Choice

a. How many Hydrogen Atoms?

b. How many Oxygen Atoms?

c. How many Atoms in all?

• a. 3

  b. 1

  c. 4

• a. 6

  b. 1

  c. 7

• a. 6

  b. 3

  c. 9

• a. 2

  b. 3

  c. 5

Multiple Choice

How many different Elements are in this Compound?

• 2

• 6

• 4

• 3

Drag and Drop

This Chemical Formula represents Nitric Acid

This formula shows there are

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molecules in total. Each molecule has ​

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Hydrogen atom(s), ​

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Nitrogen atom(s), and ​

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Oxygen atom(s).​

Drag these tiles and drop them in the correct blank above

4

1

3