The k b kb for an amine is 4.004 × 10 − 5 . 4.004×10−5. what percentage of the amine is protonated if the ph of a solution of the amine is 9.370 9.370 ? assume that all oh − oh− came from the reaction of b with h 2 o . h2o. percentage protonated: %

The percentage of amine is protonated is 63,07%

Explanation:

The reaction of an amine RNH₃ (weak base) with water is:

RNH₃ + H₂O ⇄ RNH₄⁺ + OH⁻

The kb is defined as:

As kb = 4,004x10⁻⁵ and [OH⁻] is :

1,708 = [RNH₄⁺] / [RNH₃] (1)

As the total amine is a 100%:

[RNH₄⁺] + [RNH₃] = 100% (2)

Replacing (1) in (2):

1,708 [RNH₃]+ [RNH₃] = 100%

2,708 [RNH₃] = 100%

[RNH₃] = 36,93%

Thus,

[RNH₄⁺] = 63,07%

The percentage of amine protonated is 63,07%

I hope it helps!