Identifying Mystery Gases
Part 1:Hydrogen Peroxide and manganese dioxide
You will learn how to use chemical tests to detect
oxygen, hydrogen, and carbon dioxide gases. In this
experiment, you will observe some chemical reations
that produce gases and use the tests to infer which gas
is produced
Materials: Hydrogen peroxide
Manganese Dioxide
Glowing splint
Add manganese dioxide to
the 4ml of hydrogen
peroxide. Wait 10s
Warning:
Hydrochloric acid is corrosive. Any spills on the skin, in the
eyes, or on clothing should be washed immediately with
Put a glowing splint half way
into the test tube
cold water. Report any spills to your teacher.
Hydrogen peroxide is poisonous and a strong irritant.
Manganese dioxide is also toxic. Report any spills to your
teacher
Question:
Record observations in table
Each of the following reactions produces a colourless,
odourless gas. Which gas is produced in each reaction?
Procedure :
Materials:
















Safety goggles
Apron
4 test tubes
Test-tube rack
Hydrogen peroxide
Manganese dioxide
Toothpick
3wooden splints
Candle
Lighter
Hydrochloric acid
Magnesium ribbon (3cm)
Tongs
Limewater solution
Sodium bicarbonate
Test –tube stopper
Hypothesis: predict what gas will be produced.
Pre-lab:
Read the following handout and produce a flow chart
that describes the steps for each test. Part 1 is done for
you.
1.
2.
3.
4.
Put on safety goggles.
Examine the flow chart and chart for each test.
Fill out a hypothesis for each test.
Collect 4 test tubes and place into a test tube
rack.
PART 1: Hydrogen Peroxide and Manganese Dioxide
5. Put a clean, dry test tube in the test-tube rack.
6. Pour in 4ml of hydrogen peroxide solution into
the test tube
7. Obtain a tiny amount of manganese dioxide
powder on the blunt end of toothpick.
8. Add the manganese dioxide powder to the
hydrogen peroxide. Allow the reaction to
proceed for 10s, noting any changes.
9. Bring a flaming splint to the mouth of the tube.
If nothing happens then put a glowing splint
halfway into the test tube.
10. Observe the 2 reactants upon mixing and fill out
your observation table.
PART 2: Hydrochloric Acid and Magnesium
11. In another test tube, carefully pour about 25ml
of Hydrochloric Acid into the test tube.
12. Obtain a 3cm long piece of magnesium ribbon
13. Roll the magnesium into a ball and then using
tongs carefully add the magnesium ball to the
acid. Wait 10s.
14. Bring a burning splint close to the mouth of the
test tube. If no reaction occurs, blow out the
flame, insert the glowing splint halfway into the
test tube.
15. Record your observations.
PART 3: Hydrochloric Acid and Sodium Bicarbonate.
16. Take the last two remaining test tubes and add
4mL of limewater into ONE test tube.
17. In the other tube pour 4mL of hydrochloric acid.
18. Obtain a penny sized amount of sodium
bicarbonate.
19. Slowly add the sodium bicarbonate to the test
tube containing the Hydrochloric acid.
20. After 5s, put a burning splint near the mputh of
the tube, If there is no reaction, blow out the
splint and insert a glowing splint.
21. If the splint goes out, carefully pour the gas into
the test tube containing limewater and
STOPPER.
22. Mix the contents by turning the test tube
upside down several times.
CLEAN-UP
Dispose of all the mixtures in the test tubes as directed
by your teacher.
Clean all glassware with soap and water.
Wipe down your work station.
Wash your hands.
MYSTERY GASES: THE TESTS
A common chemical reaction is combustion (burning).
OXYGEN must be present for combustion to take place.
1. Glowing splint ignites(combusts) its oxygen
HYDROGEN is very explosive when ignited.
1. A flaming splint will produce a popping sound if
hydrogen is present
CARBON DIOXIDE does not burn and does not allow
other materials to burn.
1. A burning splint will be extinguished in the
presence of carbon dioxide.
2. Carbon dioxide will change lime water cloudy.
Discussion Questions:
1. For each test you conducted, state what gas
was produced and explain HOW you knew.
a. Hydrogen peroxide and manganese
dioxide
b. Hydrochloric acid and Magnesium
c. Hydrochloric acid and sodium
bicarbonate
2. When the different chemicals were mixed in
each test tube, was a chemical or physical
change produced and why?
3. What chemical properties distinguish the
reactivity between the three mystery gases
(Combustion, not combustible or explosive)?
4. Give reasons for the following;
a. One of the gases you found is used in
fire extinguishers. Which one and Why?
b. Another gas was used for many years to
float transportation balloons. Which
one and why is this gas not used today?
c. Another gas is used in hospitals by
many patients with breathing. Which
one and why?
5. Research and state the chemical reactions that
occurred during each reaction.
Marking Scheme- Informal Mystery Gases
Flow charts
/2 T
Purpose
/1 T
Hypothesis
/3 T
Observations
/17 A
Discussion
/18 C
Conclusion
/5 C
References
/1 A