Chem 2/L ChemistryActivity Number 2ALKANES
I. Objectives:1. To describe some important physical and
chemical properties of a representative of an alkane (butane) after
performing some chemical tests.2. To describe some characteristics
properties of alkanes or saturated hydrocarbons. Materials: Butane
from butane lighter 1 piece carbon paper 0.01 M KMnO4 1 M H2SO4
bromine solution Math 4 test tubes with stopper Test tube rack 2
pipets Test tube brush Small basin Graduated cylinder 50-ml beaker
1 dropper
Procedures:A. Collection of butane sampleCollect butane in four
tubes from a butane lighter by water displacement.1. Place the test
tubes and stoppers in the water basin. Fill each test tube with
water up to the brim. Invert the over the water and see to it that
no air bubbles form inside the test tube.2. Submerge the butane
lighter under water. Place the valve under the mouth of the test
tubes and open it. Slowly release the gas by opening the valve and
collect the gas by water displacement. Cover each test tube with
rubber stopper once all the water has been displaced. Do this while
the mouth of the test tube is still submerged under the water.
B. Properties of Butanea. CombustibilityGet the last sample of
the butane collected. Get ready with a lighted match. Remove the
stopper of the test tube and ignite the gas. b. Reaction with
acidified potassium permanganateGet a sample of the collected gas
and get ready with a medicine dropperFill the dropper with
acidified KMnO4, remove the stopper of the test tube and
immediately add the acidified KMnO4 to its content. Shake well.c.
Reaction with bromine1. Get two test tube of the collected gas.
Open one test tube at a time and immediately add one ml of bromine
solution to each tube. Place the stopper on each test tube.2. Wrap
a carbon paper around one test tube and keep it inside the room.
Place the unwrapped test tube under sunlight.3. Observe both test
tubes after 7-10 minutes. Un-wrap the other test tube at the same
time to make your observation for the test tube exposed to the
light.Record all your observations and answer the questions for
research.
II. Questions for research:
1. Butane in the lighter barrel is in the liquid phase. In what
phase does it exist when you collected it? Explain what had
happened. Explain why butane easily undergoes a change in phase.2.
Is the gas combustible? Describe the characteristics of the flame
produced?3. Write the chemical reaction for the complete combustion
of the butane.4. Describe and explain your observation for the
reaction of butane to an acidified KMnO4.5. Describe and compare
your result and observation for the two test tubes in the reaction
of butane with bromine. Explain your observations.
II. METHODOLOGY
Following the schematic diagram below will show the flow of the
activity II by how it was done.
1. Preparation of the Materials 1.a Preparation of the
laboratory materials needed1.b Preparation of butane lighter
2. Collection of Sample
2.a Filling the small basin with water
2.b Filling the test tubes with water thatll be used for water
displacement [there must be no air bubbles present inside the
tubes.]
2.c Starting the water displacement method by submerging the
test tubes to the small basin with water
2.d Collecting the butane gas with water displacement method
2.e Finalizing the collection of butane gas and preparing it for
the tests for its properties
3. Properties of Butane
A. Combustibility
3.A.a Preparing the lighted match stick for the combustibility
test of butane gas
3.A.b Igniting the butane gas with a lighted match stick [Top
Most Left and Right]; thus producing an orange flame [Bottom
Centre]
B. Reaction with acidified potassium permanganate 3.B.a
Preparing the potassium permanganate
3.B.b Acidifying one (1) mL potassium permanganate (KMnO4) by
adding two (2) drops of H2SO4
3.B.c Adding the acidified potassium permanganate [Left] to the
butane gas sample; and observing the reaction(s) gained by the test
[Right]