Gimnazija Bežigrad
International Baccalaureate
Higher Level Chemistry 2021-2022
3MM/Q
EXPERIMENTAL WORK
Flame test
Candidate: Hana Sarajlić
Supervisor: Saša Cecowski
Date: 15. 9. 2021
INTRODUCTION
The aim of the experiment is to observe the characteristic colours generated by certain
metallic ions when burned. In practice it can be used to visually determine the possible
identity of an unknown metal, or a metalloid ion found in an ionic compound. When an atom
is exposed to a high temperature, one or more of its electrons gains energy and their energy
levels rise. When those said atoms return to a lower energy level, the energy they give off
expresses itself in the form of their characteristic colour. The higher the ion concentration in
the compound, the higher the intensity of the flame colour.
Variables
Independent variable:
 Ionic compound: The compound we burn, that gives off a characteristic colour when
cooled down.
Dependent variable:
 Characteristic colours: The colours that can be seen when metalloid ions that are in
the sample give off energy and gives us an idea of what the unknown compound could
be.
Controlled variables:
 The order of compounds burned. Starting with the ones that burn the fastest and
ending with the ones that take a longer time to completely burn off.
MATERIALS AND EQUIPMENT:
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Bunsen burner.
Metal rod with a nichrome wire.
Chemicals: Potassium Chloride, Calcium Chloride, Calcium Chloride, Copper Cloride,
Barium Chloride, Lithium Cloride, Souium Chloride and an unknown sample.
SAFETY NOTES: Lab coats must always be worn in the laboratory. Hands must always be
disinfected or washed before leaving the laboratory. Shoes worn must be closed as to protect
one’s feet. Contact between hands and face must be minimal.
PROCEDURE
1. Light the Bunsen burner and adjust the air flow so the flame becomes almost
colourless.
2. Clean the nichrome rod by inserting it into flame as to burn off the possible previous
residue. The process is complete when there is no colour left.
3. Dip the nichrome wire in the test tube containing the compound that is to be tested.
Hold the wire over the flame at a slight angle and observe the colour of the flame.
4. Clean the wire by holding it over the flame until said flame no longer has colour.
5. Repeat the procedure with each compound and clean the wire each time.
6. Repeat the steps with the unknown compound and clean the wire one final time.
Picture of setup
DATA COLLECTION
Design your data table to accommodate both quantitative and qualitative data. Record all your
raw data in tables. The tables should be numbered and have captions in which you briefly
describe the contents of the tables and how you recorded the results. Titles, units and the
uncertainty should be given in the headings of the tables as seen below in Table 1.
Table 1: Results of the flame test
Metal found in the salt
Flame Color and Intensity
Potassium
Light-lilac, not intense.
Calcium
Orange-red
Copper
Green-blue
Barium
Green
Lithium
Red
Sodium
Yellow
Unknown
Orange-red, presumably calcium
Underneath the table you can briefly describe the results. You can describe the main trends
and account for any anomalous result. You don’t have to discuss the significance of the results
to the aim of the investigation.
DATA PROCESSING
Data processing is distinct from data collection.
For any calculation, first annotate for the reader the intent of your calculation. Show the
equation used in symbolic form, then substitute in numbers with units. Explain any eliminated
data or special treatment of the raw data made. Organize repeated calculations into a Results
Table. Include any graphs in this section. The axes of the graphs have to be labelled with units
and the points have to be plotted correctly. Make sure that you use the correct type of graphs.
The independent variable is plotted on the x axis and the dependent variable is plotted on the
y axis.
CONCLUSION AND EVALUATION
This section will have three distinct paragraphs.
In the first paragraph, write a conclusion based on an interpretation of the gathered results.
Include % error and assessment of direction and types of errors. In this section you should
discuss the results you obtained in relation with your hypothesis if you stated any.
In the second paragraph the procedure is evaluated. You will assess the precision and/or
accuracy of your work.
In the third paragraph, evaluate the limitations in the design and execution of the
experiment, and suggest realistic ways to improve the experiment for future duplication of
findings. Compare your results with literature values if possible.
Sources:
 Flame test. [internet]. [cited on 15. 9. 2021]. Available on: https://askinglot.com/what-is-theaim-of-the-flame-test
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