# Chemistry

posted by .

A solution made up of 1.00 M NH3 and 0.500 M (NH4)2SO4 has a pH of 9.26.

a. Write the net ionic equation that represents the reaction of this solution with a strong acid.

b. Write the net ionic equation that represents the reaction of this solution with a strong base.

c. To 100. mL of this solution, 10.0 mL of 1.00 M HCl is added. How many moles of NH3 and NH4+ are present in the reaction system before and after the addition of the HCl? What is the pH of the resulting solution?

• Chemistry -

Jason, have you worked with the Henderson-Hasselbalch equation?

• Chemistry -

pH=pKa+ log(conjugate base/conjugate acid)

I have it in my notes, I just can't figure out the steps to solve this problem, or how it applies.

• Chemistry -

The base is NH3.
The acid is NH4^+.
a. With a strong acid it's the base that uses it; i.e.,
NH3 + H^+ ==> NH4^+

b. With a strong base it's the acid that uses it.
NH4^+ + OH^- ==> NH3 + H2O

millimols NH3 = mL x M = 100 x 1M = 100
mmols NH4^+ = mL x M = 100 x 0.5M x 2 = 100
mmols HCl added = 10mL x 1M = 10.

........NH3 + H^+ ==> NH4^+
I.......100...0........100
C.......-10..-10........+10
E........90....0........110

pH = pKa + log (base)/(acid_
pH = pKa + log(90/110)
Plug in pKa and solve for pH.

• Chemistry -

Ok, thank you! this makes a lot of sense. and the pKa is the -logKa? Ka=[NH4^+]=110?

• Chemistry -

Not quite.
If you use Kb for NH3 = 1.8E-5 then pKb = -log Kb = about 4.74 and since
pKa + pKb = pKw = 14, then
pKa = 14-4.74 = 9.26. Your tables may give a different value for Kb NH3 but most show 1.8E-5 or 1.75E-5

• Chemistry -

what PH would mark the end-point of a weak acid having a ka value of 0.000005 assume the salt formed to be at a molar concentration of 0.05 at the end

## Similar Questions

1. ### Chemistry

How do I make NH3 to NH4? How would write an ionic equation?
2. ### chemistry

Write a net ionic equation for the reaction of the aqueous species ammonia and hydrofluoric acid. I don't think mine is coming out right- I don't know how NH3 reacts with other species, because I end up getting hydrogen as both an …
3. ### chemistry

A 0.0875 M solution of aqueous ammonia was titrated with a solution of sulphuric acid. If 25.00 mL of the ammonia solution required 30.66 mL of the acid to reach the end-point, calculate the molarity of the acid. NH3(aq) + H2SO4(aq) …
4. ### chemistry

the question reads: a) balance the equation: H3PO4 + Ca(OH)2 --> Ca3(PO4)2 + H2O b)what mass of each product results if 750 mL of 6.00 M H3PO4 reacts according to the equation?
5. ### college chem

Two questions where I have to write a balanced net ionic equation. 1. Write a balanced net ionic equation for the reaction that occurs when aqueous solutions of sodium chromate and silver nitrate are mixed 2. Write a balanced net ionic …
6. ### Chemistry

I am having a bit of difficulty getting the net equation and the net ionic equation and the net ionic equation. I think I have the balance equation right. Thanks in advance for any help. For the acid base neutralization reaction of …
7. ### AP Chemistry

Write the balanced molecular, complete ionic, and net ionic equations for the reactions that occur when the following are mixed. (Type your answer using the format [NH4]+ for NH4+ and [Ni(CN)4]2- for Ni(CN)42-. Use the lowest possible …
8. ### AP Chemistry

Write the balanced molecular, complete ionic, and net ionic equations for each of the following acid-base reactions. (Type your answer using the format [NH4]+ for NH4+ and [Ni(CN)4]2- for Ni(CN)42-. Use the lowest possible coefficients.) …
9. ### Chemistry

Consider the reaction in aqueous solution: 6 HCl + 2 KMnO4 + 5 H2O2 ---> 5 O2 + 2 MnCl2 + 2 KCl + 8 H2O 1.) Write the total ionic equation. 2.) Write the net ionic equation. 3.) For each species (molecule or ion) in the net ionic …
10. ### General Chemistry

When a solution of nickel (II) chloride is mixed with a stoichiometric amount of colorless sodium hydroxide solution, a green, gelatinous precipitate forms. (a) Write the balanced molecular equation and the net-ionic equation for this …

More Similar Questions