LAB 16 – Qualitative Tests for Common Gases
(adapted from Flinn Scientific, Inc., Common Gases, AP6638)
All gases, though most are colorless and odorless, have physical and chemical properties that allow
chemists to detect their presence and identify them based on the reactants that produce them and the
physical and chemical properties they exhibit.
The purpose of this lab is to prepare five common gases by chemical reactions and observe their
physical and chemical properties.
This lab will be conducted in 5 stations. At each station, complete and balance the equation for the
reaction. Carry out the reaction as directed and observe the production of a common gas. Learn what
qualitative test will identify each gas.
REACTION 1
NaHCO3(aq) + HCl(aq)  H2O(l) +
______
Procedure:
1. Add 2 mL of 0.1M sodium bicarbonate to a small test tube.
2. Add 2 mL of 3 M hydrochloric acid to the test tube. Record the color and odor
of the gas.
3. Light a wood splint and insert the burning splint into the top half of the test
tube (NOT into the liquid). Record observations.
4. Empty test tube into sink and rinse with distilled water.
REACTION 2
Cu(s) + HNO3(aq) 
Procedure:
1. Add 1 mL of nitric acid to the test tube
2. Add a small piece of copper foil to the test tube and cover with parafilm.
Record color of gas as it forms. Do NOT attempt to smell the gas.
3. Place the used test tube in the rack in the fume hood.
REACTION 3
NH4Cl(aq) + NaOH(aq)  NaCl(aq) + H2O(l) + ______(g)
Procedure:
1. Add a small amount of ammonium chloride to a test tube and add about 5 mL
of water. Cover the end of the test tube with finger or thumb and mix. (wash
hands after).
2. Place test tube in beaker of hot tap water.
3. Add 10 drops of 3 M sodium hydroxide to the test tube. Swirl the test tube to
mix, and carefully observe color and odor of gas. (Do NOT sniff directly!)
4. Place a drop of distilled water on a piece of litmus paper and place the paper
on top of test tube. Record color change.
5. Empty test tube into sink and rinse with distilled water. Throw litmus paper
into trash.
(g)
Cu(NO3)2(aq) + H2O(l) + _______(g)
REACTION 4
H2O2(aq)  H2O(l) + ______(g) (catalyst MnO2 is NOT shown in equation.)
Procedure:
1. Add 5 mL of 3% H2O2 to test tube.
2. Add a small amount (= to a grain of rice) of manganese dioxide to test tube
and seal with parafilm. Gently swirl to initiate the reaction. Record color and
odor of gas. Allow test tube to sit undisturbed for 2 min.
3. Light a wood splint. Allow splint to burn briefly, and blow out flame. While the
splint is still glowing, remove parafilm and place glowing splint in top half of
test tube (NOT in liquid). Record observations.
4. Empty test tube into sink and rinse test tube with distilled water.
REACTION 5
Mg(s) +
Procedure:
1. Carefully add 5 mL of 3 M hydrochloric acid to test tube.
2. Strike a match, carefully add one piece of magnesium ribbon to the test tube,
and quickly place lit match at mouth of test tube. Record color and odor of
gas, and any other observations.
3. Empty test tube into sink and rinse with distilled water.
HCl(aq)  MgCl2(aq) + ______(g)
DATA TABLE:
Name & Formula of Gas
Color/Odor
Qualitative test results
Reaction 1
Reaction 2
(color only)
none
Reaction 3
Reaction 4
Reaction 5
QUESTIONS:
1) Consider the gases produced in this lab and identify which gas:
a. Is a component of smog/air pollution
b. Lightest element
c. Needed to burn fuel and for respiration
d. Used in production of fertilizer
e. Is combustible
f. Extinguishes a flame
g. Has a distinct odor
h. Is required for photosynthesis
2) Explain the reason for the qualitative test results for oxygen.
3) Explain the reason for the qualitative test results for ammonia.
4) List the elements that exist as gases. Which, if any, are toxic? Which are inert?
5) Research and explain in your own words how chlorine is/has been used BOTH to the benefit
and detriment of humans.