The term “Ka for the ammonium ion” describes
the equilibrium constant for which of
the following reactions?
1. NH3 + H2O ⇀↽ NH4
+ + OH−
2. NH+
4 + OH− ⇀↽ NH3 + H2O
3. NH3 + H3O
+ ⇀↽ NH+
4 + H2O
4. NH+
4 + H2O ⇀↽ NH3 + H3O
+
5. The term is misleading, because the ammonium
ion is not an acid.
6. NH4Cl(solid) + H2O ⇀↽ NH+
4 + Cl−
The way you have displayed the answers I can't tell what is what. Here is the Ka equation for the NH4^+.
NH4^+ + H2O ==> NH3 + H3O^+
Except for the missing charge on H3O^+, #4 appears the closest.
Yes, the answer is:
4) NH+4 + H2O ⇀↽ NH3 + H3O^+
Oh, the infamous "Ka for the ammonium ion"! That's a hot topic, let me tell you.
Well, to answer your question, the correct choice would be option 3. NH3 + H3O+ ⇀↽ NH+ 4 + H2O. You see, Ka represents the equilibrium constant for an acid dissociation reaction. In this case, ammonium ion (NH+ 4) acts as an acid and donates a proton to water (H2O), resulting in the formation of hydronium ion (H3O+). So, option 3 fits the bill.
But let's give a round of applause to option 5 for trying to be misleading. Sorry, ammonium ion, but you're not off the hook just yet!
To determine which reaction the term "Ka for the ammonium ion" describes, we need to compare the reactions and identify the one that involves the ammonium ion in an acid-base equilibrium.
The ammonium ion, NH4+, is formed when ammonia, NH3, acts as a base and accepts a proton, H+, from an acid. Therefore, we are looking for a reaction that involves NH3 and H+ ions.
Let's analyze each option:
1. NH3 + H2O ⇌ NH4+ + OH-
This is the reaction of ammonia acting as a base and accepting a proton from water, forming the ammonium ion and hydroxide ion. It is a valid acid-base reaction involving the ammonium ion.
2. NH4+ + OH- ⇌ NH3 + H2O
This reaction is the reverse of the previous one. It still involves the ammonium ion, but it is the conjugate acid-base reaction of the first one.
3. NH3 + H3O+ ⇌ NH4+ + H2O
This reaction involves ammonia acting as a base, accepting a proton from the hydronium ion (H3O+), and forming the ammonium ion and water. It is also an acid-base reaction involving the ammonium ion.
4. NH4+ + H2O ⇌ NH3 + H3O+
This reaction is the reverse of the third one. It is the conjugate acid-base reaction of the third reaction.
5. The term is misleading because the ammonium ion is not an acid.
This option suggests that the ammonium ion is not involved in any acid-base reaction, but it is incorrect.
6. NH4Cl(solid) + H2O ⇌ NH4+ + Cl-
This reaction involves the dissolution of solid ammonium chloride in water. It does not involve any acid-base equilibrium with ammonia and the ammonium ion.
After analyzing all the options, we can conclude that options 1 and 3 are the acid-base reactions that describe the equilibrium constant "Ka for the ammonium ion". Both reactions involve ammonia acting as a base and forming the ammonium ion.