Posted by help!!! on Monday, February 16, 2009 at 8:42pm.
what is the pH of an aqueous solution that is 0.123M NH4Cl
- chem - DrBob222, Monday, February 16, 2009 at 9:04pm
NH4Cl is a salt. It hydrolyzes, (reacts with water)(actually, the NH4^+ hydrolyzes) to give
NH4^+ + HOH ==> NH3 + H3O^+
Then Ka, since the NH4^+ is acting as an acid = (NH3)(H3O^+)/(NH4^+)
(NH3) = y
(H3O^+) = y
(NH4^+) = 0.123-y
solve for y.
You don't know Ka but you can calculate it since KaKb=Kw.
- chem - help!!!, Monday, February 16, 2009 at 9:34pm
my y = 2.25*10^-5
n what do i do
- chem - DrBob222, Monday, February 16, 2009 at 10:08pm
where did you get m?
[(NH3)(H3O^+)/(NH4^+)] = Kw/kb
(y*y/0.123-y)= 1 x 10^-14/1.8 x 10^-5
I don't know your book value for Kb for NH3 but I'm using 1.8 x 10^-5.
Then operate on the right side only to get
1 x 10^-14/1.8 x 10^-5 = 5.56 x 10^-10, then
[y^2/(0.123-y)] = 5.56 x 10^-10
Since y is small compared to 0.123, we can simplify by making 0.123-y = 0.123, then (or you can solve the quadratic if you wish)
(y^2/0.123)=5.56 x 10^-10
y^2 =5.56 x 10^-10*0.123 = 6.83 x 10^-11 and y = sqrt (...) = 8.27 x 10^-6
Convert that to pH which is approximately 5.10.
Answer this Question
More Related Questions
- Chem - 1) Which solution will have the lowest OH- A) Na2CO3 B) NaHCO3 C) NaCl D...
- Chem - What stoichiometric concentration of the indicated substance is required ...
- Chemistry - An aqueous solution is 8.50% ammonium chloride, NH4Cl, by mass. The...
- Gen. Chem 1 - The density of 18% nh4cl is 1.05 grams/ml. What mass of nh4cl is ...
- Chemistry AP - Calculate the pH of a 0.44 M aqueous solution of NH4Cl. Kb = 1.8...
- Chemistry - What are the concentrations of the following solutions: a) a 200mL ...
- Re chemistry - What are the concentrations in mass of the following solutions: ...
- college chem - how many grams of NH4Cl are required to prepare 250 mL of .122 M ...
- College Chemistry - A 0.05 molal aqueous solution boils at 373.102 K. What is ...
- chemistry - What is the of an aqueous solution that is 0.128 M NH4Cl ?