When an alkali metal dissolves in liquid ammonia the solution can acquire different colours

Monjur Alahi

When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change. 


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Salim Ahmed Kawsar

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All alkali metal dissolve in liquid ammonia giving deep blue solutions which are conducting in nature. These solutions contain ammoniated cations and ammoniated electrons as shown below:
M + ( x + y ) NH3 → M+(NH3 )x + e-(NH3)y The blue colour of the solution is considered to be due to ammoniated electrons which absorb energy corresponding to red region of the visible light for the their excitation to higher energy levels. The transmitted light is blue which imparts blue colour to the solutions.

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