MOUNT KENYA UNIVERSITY (MACHAKOS DIBEL) SCHOOL OF EDUCATION
DEPARTMENT OF EDUCATIONL MANAGEMENT AND CURRICULUM STUDIES
COURSE TITLE: INORGANIC CHEMISTRY1
COURSE CODE: BCH 1103
TITLE: LABORATORY REPORT ON FLAME TESTS
NAME: KITHULI CLIFFORD MUTETI
REG NO: BEDS/2025/65768
LECTURER’S NAME: DR. PURITY NGUI
FLAME TESTS
OBJECTIVES
1. To observe the characteristic colours imparted toa burner flame by several metal ions.
2. To determine the metal ion present in an unknown metal salt.
INTRODUCTION
When atoms are heated in a flame their electrons absorb energy and are excited to higher
energy levels (excited state). However, this state is unstable and the electrons soon return to
their ground (lower energy) state. In doing so, they release energy in the form of
electromagnetic radiation – often visible light.
Because the energy levels in each element are unique, the emitted light has specific
wavelength and appears as a characteristic flame color. This forms the basis of flame test
which are used for qualitative identification of metal ions.
EQUIPMENT MATERIALS
Beakers 250ML Distilled/ionized water
Bunsen burner & lighter Sodium Chloride (NaCl)
Weighing paper Calcium Chloride (KCl2)
Spatulas Potassium chloride (KCl)
Beakers approximately 150ML Lithium Chloride (LiCl)
Wooden splits Unknown metal salt
PROCEDURE
1. A small beaker is halfway filled with distilled water and wooden splints soaked in it
2. One soaked splint is dipped into a metal salt sample to collect a small amount of it
3. The splint coated with salt is heated in the outer edge of non-luminous flame (blue) of
the Bunsen burner
4. Observations of the color of the flame were recorded without allowing the splint to
catch fire
5. Repetition for each salt sample was done with a fresh splint and finally the test of the
unknown sample done and observations recorded
RESULTS AND OBSERVATIONS
1. Sodium Chloride burnt with bright yellow flame
2. Potassium Chloride burnt with lilac (pale violet) flame
3. Lithium Chloride burnt with crimson red flame
4. Calcium Chloride burnt with orange-red/brick red flame
5. Uknown salt burnt with a bright yellow flame
DISCUSSION/EXERCISE RESPONSES
1. Energy diagram sketch and explanation
Excited Slate
Emitted Photon Color Light
Ground slate
Electrons in a metal ion absorb heat energy and jump to higher energy levels (excited
state)
They quickly fall back to their lower (ground) energy levels
The energy difference between the levels is released as protons of light
The wavelength and thus the color of light depends on the energy released
2. Flame Test Color Table
METAL ION SALT USED FLAME COLOR
Na+ Sodium Chloride Bright yellow
K+ Potassium Chloride Lilac/Pale Purple
Li+ Lithium Chloride Crimson red
Ca+ Calcium Chloride Orange -Red/Brick Red
Unknown salt Bright yellow
3. Major difference between Alkali Metals and Calcium Flame Colors
Alkali metals which are group 1 elements such as Sodium, Potassium and Lithium produce
flame colors that are brighter and sharper due to simpler electron configurations and lower
ionization energies while Calcium, an alkaline earth metal which is group 2 element has more
electrons and a more complex energy levels structure. This results to softer or more muted
colors like orange-red. Calcium ions may not always produce as intense a color unless
properly heated.
4. Identification of unknown metal salt
The unknown metal salt produced a bright yellow flame, a characteristic of sodium ions. The
unknown metal salt is likely Sodium Chloride (NaCl) or another Spodium Compond.
CONCLUSION
The flame test is a simple yet effective method to detect the presence of certain metal ions
based on their flames color. Each element emits a distinct color due to unique electronic
transitions.
Based on the flame color observed the unknown metal salt was determined to contain Sodium
ions.
REFERENCES
1. Zumdhal, S.S & Zumdahl S.A (2014) Chemistry (9th Edition). Cengage Learning.
2. Petrucci R.H, Herring, F.G Madura , J.D & Bissonnette, C (2017) General Chemistry:
Principles and Modern Applications (11th Edition) Pearson Education
3. Clark J (2002) Flame Tests – Identifying metal ions. Chem guide. Retrieved from
https://www.chemguide.co.uk
