Law of Conservation of Mass
Lab Activity
Chapter 13
From Reactants to Products:
Let’s think about it…
When carbon burns, it reacts with oxygen to
form carbon dioxide.
The starting materials in a chemical reaction are
reactants.
The substances formed from a reaction are
products.
In Our Experiment…
What would our reactants be?
Answer: vinegar and baking soda
Write an “IF-THEN” hypothesis in the
margin of your composition notebook on
page 9.
Law of Conservation of Mass:
Atoms are never lost or gained in a chemical
reaction.
(They are just rearranged.)
Every atom in the reactants becomes part of the
products.
The chemical equation must be balanced…we will
learn all about this later this week!!!
The total mass of the reactants will be the same
as the total mass of the products.
Law of Conservation of Mass—mass can’t be
created or destroyed
So…if you started with 20 total atoms on the
“reactants” side, then you should have 20 total
atoms on the “products” side.
On page 9…
Draw the following table:
Mass of Reactants
Mass of Products
As a group…
STEP 1:
Measure the mass of the filter paper.
STEP 2:
Measure out 5 grams of baking soda.
STEP 3:
Place the 5 grams of baking soda into the baggie.
STEP 4:
Using the funnel and graduated cylinder, measure
out 5 mL of vinegar.
STEP 5:
Place the 5 mL of vinegar into the plastic film
canister. Put the lid on the canister.
STEP 6:
Carefully place the canister into the baggie.
Squeeze the air out of the bag. Seal the bag.
STEP 7:
Measure the mass of the baggie and its contents.
Record the mass in your table.
STEP 8:
Keeping the bag closed, open the canister in the
bag. Mix the vinegar with the baking soda.
Record your observations under your table.
STEP 9:
When the reaction has stopped, measure the mass
of the bag and its contents. Record the mass.
STEP 10:
Compare the mass of the materials before the
reaction and the mass of the materials after the
reaction. Each of you explain your observations
on the index cards at your lab stations…this is
what you will turn in to me.
Clean Up…
1.
2.
3.
4.
5.
6.
7.
Set the triple-beam balance to zero.
Rinse out the canister.
Throw away your baggie.
Place the filter paper on the balance.
Set your supplies in a neat, organized way.
Push in your stool.
Quietly return to your seat.
On the back of your index card…
Answer the following:
I dropped two Mentos into a 2L bottle of Diet Coke.
Within seconds from dropping the candy into the soda, a
fountain of liquid fizzed up over 2 feet!
1. What were my reactants?
2. If I measured the mass of the Mentos and Diet Coke
before the reaction, how would it compare to the mass
of the materials after the reaction according to the law
of conservation of mass?