How can I complete the following equation: #CH_3CH_2NH-CH_3 + HBr ->?#
You have to recognize that this is an acid-base neutralization reaction.
HBr is a strong acid.
CH₃CH₂NHCH₃ is an amine. Amines are bases, because of the lone pair electrons on the N atom.
According to Brønsted-Lowry theory, the acidic HBr will transfer a proton to the basic amine, leaving behind a Br⁻ ion.
The amine will accept the H⁺ and become [CH₃CH₂NH₂CH₃]⁺.
So the equation is CH₃CH₂NHCH₃ + HBr → [CH₃CH₂NH₂CH₃]⁺ Br⁻.