Final answer:
When potassium ignites during its reaction with water, it produces a lilac or light purple flame color due to the excitation and relaxation of electrons in the potassium atoms.
Step-by-step explanation:
The flame color when potassium ignites during its reaction with water is typically described as a lilac or light purple color. This vivid hue is due to the excitation of electrons in the potassium atoms, which release energy in the form of light when they return to their ground state. Potassium is a highly reactive alkali metal and reacts vigorously with water, producing hydrogen gas and heat, which may ignite the hydrogen gas, leading to the characteristic flame color.
Potassium must be handled with care as it reacts rapidly with water, and it is typically stored under oil to prevent unwanted reactions with air or moisture. Like other alkali metals, when potassium reacts with water, it forms a strong base called potassium hydroxide (KOH), along with hydrogen gas (H2).