In the balanced equation (CH3)3N:BH3, the Lewis acid is BH3 (borane), because it accepts an electron pair from N(CH3)3 (trimethylamine), which is the Lewis base.
To identify the Lewis acid in the given balanced equation, we need to recognize the reactant that is electron-deficient and can accept an electron pair.
In the equation (CH3)3N:BH3, the Lewis acid is BH3 (borane).
This is because BH3 has an incomplete octet and can accept an electron pair to complete its octet.
The compound N(CH3)3 (trimethylamine) acts as a Lewis base as it donates an electron pair to borane during the formation of the adduct (CH3)3N:BH3.
The symbol ":" indicates that the nitrogen atom in N(CH3)3 donates its lone pair to the boron atom in BH3, forming a dative covalent bond.