Law of Conservation of Mass - Lesson 7.2.1

Law of Conservation of Mass
Lesson 7.2.1

By Laura O'Neill

Dropdown

Anything that has mass and takes up space is an example of​

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. The smallest unit of a chemical element is an ​

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. If two or more elements are bonded together then it is called a ​

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. The process that rearranges the atoms of a substance is called ​

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.

​chemical - a substance with a specific composition
equation - math statement that shows two sides are equal


A model of a chemical reaction that uses element symbols to show what happens.

Chemical Equation

​Law - a sta2tement about a phenomenon that implies a cause and effect between observed objects. Many times it is mathematical like: E=mc

conservation - conserve - save or prevent
Mass - amount of matter in an object

A scientific principle stating that mass cannot be created or destroyed.

Law of Conservation of Mass

​Notebook
Page 146

Open Ended

What happens during a chemical reaction?

A chemical change occurs and creates a new substance.

During the chemical reaction, the atoms get rearranged to form something new.

​It can happen anywhere!
Even your stomach.

A scientific Law is:

- something in nature that scientists notice

- it always seems to be true

- it is supported by lots of observations

​

​Remember....

​Matter cannot be created or destroyed.

​The amount of matter in a system stays constant during a chemical change.
See formation of water below!

Law of Conservation of Mass

​Notice that there is 2g of H and 16g of O that forms 18g of water.
2 + 16 = 18

Multiple Choice

Sometimes mass is created during a chemical reaction.

• True

• False

C₄H₈O₂

​How many?
Carbon =
Hydrogen =
Oxygen =

​Let's Review Formulas

NO₂






Al₂(SO₄)₃

​Formulas

​How Many?
Nitrogen =
Oxygen =



How many?
Aluminum =
Sulfur =
Oxygen =

IF we put these formulas together, they form chemical equations.

We use chemical equations to model the way atoms are rearranged during a chemical reaction.

​The arrow is like the equal sign in a math equation.

There are Carbon, Oxygen, and Hydrogen atoms on BOTH sides of the arrow.

They are remixed to form new compounds but there are no new elements added.

​This supports the Law of Conservation of Mass!

Multiple Choice

The beginning of the chemical equation is: 6CO₂ + 6H₂O -> ___

There are 6 atoms of carbon in the first half of the equation, so how many will be on the right?

• 2

• 3

• 6

• 12

​See you Monday for Chemical Equations!