Which cation produces a crimson red flame during a flame test?

The cation that produces a crimson red flame during a flame test is lithium (Li⁺). When lithium salts are introduced to a flame, the heat excites the lithium ions, causing them to emit light at specific wavelengths. The characteristic crimson red color corresponds to the wavelengths emitted, particularly around 670 nm. This vivid color is distinct and can be used as a key identifier for lithium when performing qualitative analysis.

Other cations produce different flame colors, such as sodium, which gives a bright yellow flame, potassium that results in a lilac or light purple flame, and calcium that produces an orange-red flame. Recognizing these unique flame colors is important in identifying metal ions in compounds.