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what is an ammonium ion ---

ammonium ion nh3+ or nh4+
NH4+
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alevel-up
OP
7
Original post by BobbJo
NH4+


how come in the reaction of alpha amino acids the nh3+ ion reacts to form a salt with an acid?
Original post by alevel-up
how come in the reaction of alpha amino acids the nh3+ ion reacts to form a salt with an acid?


It's not the NH3+ ion which reacts with an acid. It's the amine RNH2 which reacts

The equation is H2NCHRCOOH + H+ -> H3N+CHRCOOH
Reply 4
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alevel-up
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Original post by BobbJo
It's not the NH3+ ion which reacts with an acid. It's the amine RNH2 which reacts

The equation is H2NCHRCOOH + H+ -> H3N+CHRCOOH


but then i thought the definition of a salt is the h+ is replaced by a metal or AMMONIUM ion. in here it replaces by the nh3+????
Original post by alevel-up
But then, I thought: "the definition of a salt is that the H+ is replaced by a metal or AMMONIUM ion." In here, it is replaced by the NH3+?

Google gives
salt : "any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation."
Wikipedia gives
"In chemistry, a salt is an ionic compound that can be formed by the neutralization reaction of an acid and a base."
Reply 6
Avatar for sotor
sotor
14
in acidic conditions the amino acid would not form a salt, but the nitrogen atom would have 3 hydrogens bonded to it and the main carbon atom with an overall charge of +1 (NH3CHRCOOH)

alkali conditions could give a salt, e.g. NH2CHRCOO-Na+ with the reagent NaOH

the textboom definition of a salt is confusing and quite limiting, i wouldnt worry about the definition of a salt. there is no replacement of H+ in either reaction, but either addition of H+ to the amino acid (acidic conditions) or donation of H+ (alkali conditions)
(edited 5 years ago)

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