The law of
conservation of
matter states that
matter cannot be created or destroyed in an ordinary chemical reaction. Another way of stating this is that the
mass of products of a chemical reaction is always equal to the
mass of the reacting materials. No one has ever found an exception that does no fit this law. Your task is to devise and conduct an
experiment that tests the law of
conservation of matter.
You may study one of two reactions:
- Burning a wax candle
The
solid wax reacts with oxygen in the air, forming carbon dioxide
gas and water vapor.
OR
- The alka seltzer reaction
Alka seltzer tablets contain citric
acid and baking soda. When added to water, the reaction produces carbon dioxide gas, water, and a soluble
compound called sodium citrate.
Equipment and Materials:
Burning of Wax
|
Reaction of alka seltzer
|
Triple beam balance
|
Triple beam balance
|
4 birthday candles
|
1 balloon
|
Matches
|
Water
|
|
2-liter soda bottle
|
Bottles with stoppers
|
4 alka seltzer tablets
|
|
String
|
Grading Scale:
Your lab report will be graded on the following criteria:
- The problem is clearly defined.
- An appropriate experimental design has been selected and employed.
- Reasoning is logical and explained thoroughly.
- Inferences and conclusions are supported by appropriate observation or data.
- There are few misconceptions or serious errors.
- The methods and results are communicated clearly enough that the reader could easily repeat the experiment.
You will have one class period to conduct the experiment. You will have a portion of another class period to write it up in your lab book.
You must show mathematically, using your data, that the total
mass of the reactants equals the total
mass of the products in a closed system. If you are investigating an open system, in which gaseous products escape, show that the initial
mass is greater than the final
mass of the system.