the pH of a .050 M ammonium chloride solution was experimentally determined to be 5.45. Write the equation for the chemical reaction that determines the pH
...............NH4^+ + H2O ==> NH3 + H3O^+
Thank yo, that' what I had, but I just wanted to make sure. Now how do I find the equilibrium constant? I have that the Ka = 3.55 *10^-6 and the ice table is as follows
NH4^+ + H2O ==> NH3 + H3O^+
I .05 0 0
C -x +x +x
E .05 - x x x
K = x^2 / .05 since x is small
x should be under each product not grouped together, this computer grouped them all together erroneously
You can use .......... as a way of spacing. It isn't perfect but it's better than letting the computer do it. It looks like this.
..................NH4^+ + H2O ==> NH3 + H3O^+
I................0.05..........................0...........0
C................-x.............................x...........x
E...............0.05-x........................x...........x
Keq= [(x)(x)/(0.05-x)]
Often these problems ask for Ka for the acid (the NH4^+) and that becomes
Ka for NH4^+ = (Kw/Kb for NH3) = x^2/0.05 which gives you Kb and that translates to Ka for the salt.
@DrBob222 okay, I have the ice table correct, i calculated the Ka for the NH4 which is 3.55*10^-6 and calculated the Kb for NH3 which is 2.82*10^-9. I'm just really stuck on finding the Equilibrium constant for the entire reaction.
I wrote Keq in my earlier post. Isn't Keq the same as Ka for NH4^+? Some may want to include (H2O) as a part of Keq; however, that's essentially a constant at 55.5 M and in most cases is not included as part of K.
Keq = (NH3)(H3O^+)/(NH4^+) = [(x)(x)/0.05-x]
To determine the equation for the chemical reaction that determines the pH of the ammonium chloride solution, we need to consider the hydrolysis of ammonium chloride.
Ammonium chloride (NH4Cl) is a salt that can undergo hydrolysis when dissolved in water. Hydrolysis is a reaction with water molecules that produces either hydronium ions (H3O+) or hydroxide ions (OH-).
In this case, the hydrolysis of ammonium chloride can be represented by the following equation:
NH4Cl + H2O ⇌ NH4OH + HCl
In this equation, NH4Cl is the ammonium chloride, H2O is the water, NH4OH is the ammonium hydroxide, and HCl is the hydrochloric acid.
The ammonium chloride reacts with water to form ammonium hydroxide and hydrochloric acid. The ammonium hydroxide can further react with water to produce hydronium ions (H3O+), which determine the pH of the solution.
NH4OH + H2O ⇌ NH3 + H3O+
In this reaction, NH4OH is the ammonium hydroxide, H2O is the water, NH3 is the ammonia, and H3O+ is the hydronium ion.
The production of hydronium ions (H3O+) in the hydrolysis reaction is responsible for the solution's acidity, which is indicated by the measured pH value of 5.45.