Can you state the Law of Conservation of Mass?

Obviously the Law of Conservation of Mass says that mass is conserved. What does this mean?

If mass is conserved it means that the mass is always the same or does not change. The Law of Conservation of Mass applies to chemical changes. When considering a chemical change this would mean that the total mass of all of the reactants in the chemical reaction is equal to the total mass of products in the chemical reaction.

This then can be shown through experiments.

Activity

Select an experiment that will show you that mass is conserved during a chemical reaction. Then perform this experiment, recording your data and observations. Write a conclusion to your experiment: "Did you see from your experiment that mass is conserved?".

Pick your experiment from one of these or find a different one but have it approved by your teacher.

Choice 1

Textbook:

• Physical Science An Introductory Study - Do Investigation 7.7 page 166 and 167 (See pictures)
• Discovering Physical Science - Do Investigation 17.2 page 188 and 189

Choice 2

Online: Go to site a

Choice 3

Online: Go to site b

Assignment

In this assignment you will:

• use skills you developed in writing word equations
• apply the law of conservation of mass

The law of conservation of mass will allow us to determine the amount of a missing reactant or product that was involved in a chemical reaction.

For example, if you were told that 4 grams of hydrogen reacted with some oxygen to make 36 grams of water then you could figure out how much oxygen must have been used by applying the law of conservation of mass.

Write a word equation:	hydrogen + oxygen water
Write the masses of each substance given in the question	4 g	?	36 g
Use the law of conservation of mass (mass of reactants = mass of products)	4 + ? = 36
Solve to find the missing value	? = 36 - 4 ? = 32 So 32 grams of oxygen were used

What to do?

Look at another example

Start the assignment

Assessment

Each question in your assignment is worth 2marks. Your score will be tallied and recorded electronically. (I hope it works!)