Consider the ionization constants hypochlorous acid (HOCl) : Ka = 3.5 × 10−8; ammonia (NH3) : Kb = 1.8×10−5. A solution of ammonium hypochlorite (NH4OCl) is
1. acidic, because the cation hydrolyzes to a greater extent than the anion.
2. basic, because the anion hydrolyzes to a greater extent than the cation.
3. basic, because the cation hydrolyzes to a greater extent than the anion.
4. neutral, because the cation and the anion hydrolyze to the same extent.
5. acidic, because the cation and the anion hydrolyze to the same extent.
6. acidic, because the anion hydrolyzes to a greater extent than the cation.
7. basic, because the cation and the anion hydrolyze to the same extent.
8. neutral, because the cation hydrolyzes to a greater extent than the anion.
9. neutral, because the anion hydrolyzes to a greater extent than the cation.
10. neutral, because NH4OCl is a weak base/weak acid salt.
Why don't you calculate the K for the anion and cation?
OCl^- + HOH ==> HOCl + OH^-
Kb for OCl^- = Kw/Ka for HOCl = ??
NH4^+ + H2O ==> H2O^+ + NH3
Ka for NH4^= Kw/Kb for NH3 = ??
The larger K for the cation or anion will be the one that predominates.
I can't find it on the web nor in any of my most recent texts but when I took quant they taught me that the salt of a weak acid and weak base had (H^+) = sqrt(KwKa/Kb)
You can read about NH4ClO in aq soln here, along with the answer.
http://chemistry.about.com/od/acidsbases/a/aa110204a.htm
Well, let's break it down and see what we get. The Ka for hypochlorous acid (HOCl) is 3.5 × 10−8, which is a small number. That means it's a weak acid. On the other hand, the Kb for ammonia (NH3) is 1.8 × 10−5, which is also small, so it's a weak base.
Now, when we have a solution of ammonium hypochlorite (NH4OCl), we can see that it can hydrolyze into ammonium ion (NH4+) and hypochlorite ion (OCl-).
Since both NH4+ and OCl- are derived from weak acids and bases respectively, we can safely say that the hydrolysis of both ions will be negligible. Therefore, the answer is 4. neutral, because the cation and the anion hydrolyze to the same extent.
Just like an uneventful party where everyone's behavior is equally unenthusiastic, the hydrolysis of NH4OCl is neutral!
To determine whether the solution of ammonium hypochlorite (NH4OCl) is acidic, basic, or neutral, we need to compare the hydrolysis of the cation and the anion.
The hydrolysis of NH4OCl can be represented by the following equations:
NH4OCl + H2O → NH4OH + HOCl
The cation ammonium (NH4+) is derived from the weak base ammonia (NH3), which undergoes hydrolysis in water:
NH4+ + H2O ⇌ NH4OH + H3O+
The anion hypochlorite (OCl-) is derived from the weak acid hypochlorous acid (HOCl), which also undergoes hydrolysis in water:
OCl- + H2O ⇌ HOCl + OH-
Comparing the equilibrium expressions for the hydrolysis of the cation and the anion, we can determine the relative extent of hydrolysis:
For the cation: NH4+ + H2O ⇌ NH4OH + H3O+
The equilibrium expression is: [NH4OH][H3O+]/[NH4+]
For the anion: OCl- + H2O ⇌ HOCl + OH-
The equilibrium expression is: [HOCl][OH-]/[OCl-]
Given that the ionization constant of HOCl (Ka) is much smaller than the ionization constant of NH3 (Kb), we can conclude that [HOCl] is significantly smaller than [NH4OH]. This indicates that the cation NH4+ hydrolyzes more extensively than the anion OCl-.
Therefore, we can conclude that Option 1 is the correct answer:
1. acidic, because the cation hydrolyzes to a greater extent than the anion.
To determine whether a solution of ammonium hypochlorite (NH4OCl) is acidic, basic, or neutral, we need to consider the hydrolysis of its cation (NH4+) and anion (OCl-).
First, let's consider the hydrolysis of the cation NH4+:
NH4+ + H2O ⇌ NH3 + H3O+
NH4+ acts as an acid in this reaction by donating a proton (H+), producing ammonia (NH3) and a hydronium ion (H3O+). The extent of hydrolysis of the cation NH4+ is determined by the equilibrium constant for this reaction, which is the ionization constant Kb for ammonia.
Therefore, to determine if the cation hydrolyzes to a greater extent than the anion, we compare the ionization constant Kb for ammonia to the ionization constant Ka for hypochlorous acid.
Given that Ka = 3.5 × 10^(-8) for HOCl (acid) and Kb = 1.8 × 10^(-5) for NH3 (base), we can see that Kb is greater than Ka. This means that the cation NH4+ hydrolyzes more than the anion OCl-.
Thus, the correct answer is option 3: basic, because the cation hydrolyzes to a greater extent than the anion.
By considering the ionization constants and the hydrolysis reactions of the cation and anion, we can determine the pH behavior of the solution of ammonium hypochlorite (NH4OCl).