The color of lithium chloride (LiCl) observed during flame test was
A. Black
B. Red
C. Yellow
D. Blue
E. Green
The correct answer and explanation is:
The correct answer is B. Red.
During a flame test, lithium chloride (LiCl) produces a distinct red color. The flame test is a qualitative analysis used to detect the presence of certain metal ions based on the characteristic color they emit when heated in a flame. When lithium chloride is introduced into a flame, the metal ions absorb energy and move to higher energy states. As these excited electrons return to their ground state, they release energy in the form of light. The wavelength of this light corresponds to specific colors, and for lithium chloride, it falls within the red region of the visible spectrum.
The color observed in a flame test is dependent on the specific energy levels of the metal’s electrons. Each metal ion has a unique set of energy levels, leading to different wavelengths of light being emitted. Lithium, a member of the alkali metals, exhibits a strong red flame, which is a key feature used in identifying it in flame tests. This red emission is primarily due to a transition of electrons in the lithium ion, specifically between the 2p and 2s orbitals.
This test is often used in chemistry labs to identify alkali metal salts, as each of the alkali metals (like sodium, potassium, and lithium) produces a characteristic flame color. For example, sodium chloride (NaCl) gives off a bright yellow flame, potassium chloride (KCl) shows a lilac or light purple flame, and lithium chloride is identified by its red flame.