Post a New Question

Chemistry

posted by .

The pK3 of formic acid is 3.75
A)what is the pH of a buffer in which formic acid and sodium formate have equimolar concentration?
B)what is the pH of a solution in which the sodium formate is 10M and the formic acid is 1M?

  • Chemistry -

    I don't believe formic acid has a pK3. You must mean pKa.
    a. pH = pKa + log (base)/(acid)
    Since base = acid then base/acid = 1; log 1 is zero and pH = pKa.

    b. Use the Henderson-Hasselbalch equation above and substitute for base and acid then calculate pH.

  • Chemistry -

    Can you explain it better we JUST started this section and im having a hard time with knowing what to put where when it comes to the solutions. what is the acid and what is the base

  • Chemistry -

    a. pH = pKa + log(base)/(acid)
    pH = 3.75 + log(x)/(x) (the problem just says base = acid so I've called that x.
    pH = 3.75 + log(1)
    pH = 3.75 + 0
    pH = 3.75

    b.
    HCOOH = formic acid = acid = 1.0M
    HCOONa = sodium formate = base = 10M
    pH = 3.75 + log (10)/(1)
    Solve for pH You should get 4.75.
    Acids/bases are described with the Bronsted-Lowry theory as
    HA = acid
    HA + H2O ==> H3O^+ + A^-
    HA is the acid and A^- is its conjugate base.
    H2O is the base and H3O^+ is its conjugate acid.
    How do you know which is which? The acid is the one with more atoms; the base is the one with fewer H atoms. Look at HA. HA and A. HA is the acid because it has more H atoms than the A. A is the base becasuse it has fewer H atoms than HA.
    H2O/H3O^+. H3O^+ has more H atoms; it's the acid. H2O has fewer H atoms; it's the base.

  • Chemistry -

    Thank you :) this helped a lot!

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. AP Chemistry

    A buffer solution contains .4mol of formic acid, HCOOH and a .6mol of sodium formate, HCOONa, in 1L of solution. Ka of formic acid is 1.8 x 10^-4. a) calculate pH b) if 100ml of this buffer solution is diluted to a volume of 1L with …
  2. Chemistry

    A buffer is prepared by mixing 0.30 mole of formic acid (HCNO2) and 0.20 mole of sodium formate (NaCHO2) in enough water to make 0.50 liter of solution. Ka of formic acid is 1.7 x 10-4. Calculate the pH of the resulting buffer solution.
  3. Chem II

    Find the mass of sodium formate that must be dissolved in 200.00cm^3 of a 1.0M solution of formic acid to prepare a buffer solution with pH=3.40?
  4. Chemistry-need help ASAP

    15 ml of 3.0 M NaOH are added to the following: 500.0 ml of pure water 500.0 ml of 0.1 M formic acid 500.0 ml of 0.1 M formate of potassium 500.0 ml of a solution containing 0.1 M formic acid and 0.1 M formate of potassium. Calculate …
  5. Chemistry

    20.0 ml of 1.00 M formic acid are combined with 10.0 ml of 1.00 M sodium formate. Calculate the expected pH. Ka for formic acid is 1.77 x 10^-4
  6. Chemistry

    What is the solubility of CaF2 in a buffer solution containing 0.45M formic acid and 0.20M sodium formate?
  7. chemistry

    What mass of solid sodium formate (of MW 68.01) must be added to 115 mL of 0.57 mol/L formic acid (HCOOH) to make a buffer solution having a pH of 4.16?
  8. chemistry

    Describe the laboratory preparation of z1Litre of 1.3M formic acid buffer of pH 3.9 from solid sodium formats (molecular weight =68) and formic acid liquid 30% pure (Density of formic acid = 1.029g/ml, pKa = 3.75)
  9. Chemistry

    Explain the laboratory preparation of one Litre of 1.3M formic acid buffer of pH 3.9 from solid sodium formate (molecular weight =68) and formic acid liquid 30% pure (Density of formic acid = 1.029g/ml, pKa = 3.75)
  10. chemistry

    Given a PH of buffer solution is 4.23 made from 0.35 formic acid. Calculate the concentration of formate.The constant dissociation for formic acid is 3.75

More Similar Questions

Post a New Question