Chemistry

posted by .

Buffers- Common Ion effect

IS this Correct

Calculate the pH of a aqueous solution containing 0.15 M HNO2 and 0.20 M NaNO2 (aq). The Ka of nitrous acid is 4.0*10^-4.


HNO2 + H20 <--> NaNO2- + H30^+
Inital 0.15 0.20 X
Final 0.15 0.20


Ka= [H30+][NaNO2]/ [HNO2]
4.0*10^-4 = [H30+][0.20]/[0.15]
3.0*10^ -4 = H30+

pH= 3.52

  • Chemistry -

    The answer is correct. The methodology is not.You made several errors (equation, Ka expression wrong, etc and other errors in substitution but all of the errors canceled out to give you the correct answer). Use the Henderson-Hasselbalch equation.
    pH = pKa + log (base/acid)
    pH = 3.40 + log(0.2/0.15) = 3.52

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    A buffer is prepared by dissolving .0250 mol of sodium nitrite, NaNO2, in 250.0 mL of .0410 M nitrous acid, HNO2. Assume no volume change after HNO2 is dissolved. Calculate the pH of this buffer. My book does a poor job of explaining …
  2. chem

    What volumes of 0.53 M HNO2 and 0.46 M NaNO2 must be mixed to prepare 1.00 L of a solution buffered at pH = 3.55?
  3. Chemistry

    What volumes of 0.46 M HNO2 and 0.54 M NaNO2 must be mixed to prepare 1.00 L of a solution buffered at pH = 3.40?
  4. Chemistry

    If a researcher needs 0.50 L of 3.0 M nitrite buffer at pH 3.00, then she knows that the concentration of nitrous acid (conjugate acid) plus the concentration of nitrite anion (conjugate base) must equal 3.0 M. She must then calculate …
  5. Chemistry

    At 298 K, nitrous acid (HNO2) dissociates in water with a Ka of 0.00071. a)Calculate G° for the dissociation of HNO2. (Use Ka to calculate the answer.) b) Calculate G if [H3O+] = 0.00070 M, [NO2 - ] = 0.16 M, and [HNO2 ] = 0.21 M.
  6. chemistry

    Calculate the pH at the point in the titration of 25.00 mL 0.108 M HNO2 at which 10.00 mL 0.162 M NaOH have been added. For HNO2, Ka=5.1 x 10^-4 and: HNO2 + OH- -----> H2O + NO2- I know that HNO2 is a weak acid and NaOH is a strong …
  7. CHEMISTRY

    How many grams of NaNO2 should be dissolved in 500cm3 solution of nitrous acid (HNO2) with concentration of 0.03mol/dm3 if we wish the solution to show a pH of 3.2 Ka = 4.5 * 10^-4 M(NaNO2) = 69 g/mol
  8. Chemistry

    What is the hydronium ion concentration in a solution 0.150M in HNO2 and 0.300M in NaNO2?
  9. Analytical Chemistry

    A 500-mL buffer was prepared and it is 0.300 M in nitrous acid (HNO2 , Ka = 4.0 x 10-4) and 0.200 M in sodium nitrite, NaNO2. What will be the pH of this solution after adding 1.00 mL of 6.00 M HCl?
  10. Chemistry

    How many grams of NaNO2 must be added to 1 liter of 1.00 M HNO2 solution in order to prepare a buffer solution with pH = 4.14?

More Similar Questions