Law of Conservation of Mass

Law of Conservation of Mass

by Rozaleth Tenga

Poll

When I bake, the mass of my ingredients would be different from the mass of my bread.

• Yes

• No

Poll

When I bake, I destroy some of the ingredients which leads to less mass afterwards.

• Yes

• No

Poll

When I bake, I create new matter. 

• Yes

• No

​Law of Conservation of Mass

​This law states that

​

​Mass is neither created nor destroyed during a chemical reaction.

​Mass is conserved

​Law of Conservation of Mass

​The mass of your reactants will be equal to the mass of your products.

​

​

​Mass_reactants = Mass_products

​

Mass_reactant + Mass_reactant = Mass_products

So where does the other matter go?

• When you bake you are doing a chemical reaction

• The chemical reaction just changes the ingredients into something else as it interacts with other ingredients.

Open vs Closed System

• It's easier to observe the law of conservation of matter in a closed system than an open system

• ​Open System

  • ​matter and energy goes in and out of the system freely

• ​Closed System

  • ​no matter nor energy goes in and out of the system

Open vs Closed System

• It's easier to observe the law of conservation of matter in a closed system than an open system

• ​Open System

  • ​matter and energy goes in and out of the system freely

• ​Closed System

  • ​no matter goes in and out of the system

  • ​energy may go in and out though

Isolated System

• When a system is isolated, no matter nor energy can go in or out.

Multiple Choice

Is this classroom an open, closed, or isolated system?

• Open

• Closed

• Isolated

Multiple Choice

Is the outer space an open, closed, or isolated system?

• open

• closed

• isolated

Multiple Choice

Hydro Flask promises that your water will stay cold for 24 hours. Is this an open, closed, or isolated system? 

• open

• closed

• isolated

​Let's Apply

​I have 10 g of hydrogen (H) and I reacted it with oxygen. If my product's mass is 15 g, how much oxygen did I use?

Multiple Choice

How much oxygen did I use?  

• 5 g

• 5

• 10 g

​Let's Apply

I reacted aluminum with liquid bromine. I used 10.3 g of aluminum and 100.0 g of liquid bromine. What would be the mass of my product?

Multiple Choice

How much aluminum bromide (product) will you produce?

• 10.3 g 

• 110.3 g

• 100.0 g

• 0.00 g

​Today's Activity - Lab!

• ​Your table will be your group.

• ​You will be provided your materials on your table

• ​You will stay on your tables for the duration of the lab

• ​Work on the lab report when you are done with the lab.