Learning Check
1. Name one compound you used during
Friday’s lab.
2. Is CaCO3 ionic or covalent
3. Name CaCO3
1. Na2CO3 (sodium carbonate), CaCl2 (calcium chloride), HCl
2. Ionic
3. Calcium carbonate
How to write a lab report
For Mr. Harwijne’s Class
Date: Feb-18-14
Investigating Mass Changes in a Reaction
Partner: John Smith
Lab # 4-3A
Name: Emma Johannson
Purpose: To compare the masses of products and reactants in a chemical reaction.
Hypothesis: I predict that the mass of the products will be equal to the mass of the
reactants because Antoine and Marie-Anne Lavoisier developed the law of
conservation of mass, and the reaction occurred in a sealed container (pg. 205 tb).
Apparatus
& Materials:
Please see page 203 of BC Science 10 textbook.
Small test tube: 8 mL volume
Small erlenmeyer: 250 mL volume
Switched cobalt chloride for calcium chloride
Procedure: Please see page 203 of BC Science 10 textbook. Modifications below:
• Pour ~50mL Na2CO3 into Erlenmeyer
• Fill test tube 2/3 full with CoCl2
• Pour some HCl into test tube to dissolve product, swirl, then pour test
tube contents into Erlenmeyer and gently swirl. Rinse with cold water.
Diagram:
N/A
Observations:
Compound
Chemical Formula
Colour
State
Cobalt Chloride
CoCl2
Pink
Aqueous
Sodium Carbonate
Na2CO3
Milky white
Aqueous
Cobalt Carbonate
CoCO3
Blue
Solid
Colourless
Aqueous
Mass of sealed Erlenmeyer before mixing (reactants) : ____________g
Mass of sealed Erlenmeyer after mixing (products) : ____________g
Sample Calculations: N/A
Graph:
N/A
Questions:
1. Broken glassware belongs …
2. When a chemical spills on me, the safe thing to do is to immediately wash it off
either in a ____, the ______, or the ________ station, and to tell the _______ as
soon as possible. If a chemical spills on the counter or the floor, I will immediately
____ the teacher, or ____ it up with _____ _____ if it’s water.
3. If there’s a fire, I will …
4. To safely pour chemicals, I must hold my palm against ___ _____ of the bottle,
and never point it towards anyone’s, or my own ____.
5. The reaction I investigated today was that of cobalt (II) chloride and sodium
carbonate.
Co2+ Cl 1- and Na1- CO3- 
6. Cobaltous carbonate is a common name for one product, and the other product is
commonly known as _____ ____.
7. Cobalt (II) carbonate is an intermediate in cobalt ores from mining, and it’s also
used as a pigment. ______ ________ can be found …
Conclusion:
In this lab, I compared the masses of products and reactants in the chemical
reaction of cobalt (II) chloride with sodium carbonate. I found that my hypothesis was
not supported because the mass of the products was not equal to the mass of the
reactants. The mass of the reactants was __________g, while the mass of the
products was __________g. I suspect my results were thrown off because …