CHEM HELP...PLEASE!!

posted by .

A solution of volume 80.0 mL contains 16.0 mmol HCHO2 and 9.00 mmol NaCHO2.
If 1.00 ml of 12 M HCl is added to this, what will be the resulting pH?

  • CHEM HELP...PLEASE!! -

    Use the Henderson-Hasselbalch equation.
    pH = pKa + log (base/acid)
    First, however, you need to make some adjustments to the acid/base because you have added some HCl to it.
    HCOOH = 16.0 mmole initially.
    HCOONa = 9.00 mmol initially. Adding 1.00 mL of 12 M HCl adds 12 x 1 = 12 mmole (is that 12 or 12.0 or 12.00 mmole?) to this base. Therefore, 9.00 + 12.0 = 21.0 mmole base.
    pH = pKa + log[(21.0)/(16.0)] = ??
    If your prof is picky, s/he will not like this BECAUSE (base) and (acid) are concentrations and not mmols. Technically, then, the concn is mmols/mL = 21.0/81.0 for (base) and 16.00/81.0 for (acid) so the equation is
    pH = pKa + log[(21.0/81.0)/(16.0/81.0)] = ??. You will note that the 81.0 mL volume cancels and some profs just don't put it there. I ALWAYS counted off for not including the volume; however, since it ALWAYS cancels, I would allow the student to use V as in
    pH = pKa + log [(21.0/v)/(16.0/v)] = ??. That way the student let me know that a volume went there but it would cancel and never entered into the calculation.

  • CHEM HELP...PLEASE!! -

    Sorry, there's one thing I don't understand. If an acid is being added to a buffer solution, shouldn't the pH decrease? By following your method, the answer I'm getting is greater than the original pH.

  • CHEM HELP...PLEASE!! -

    Buffers increase ph of acids, they buffer the degree at which acids affect solutions

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. mastering chemistry

    A solution of volume 80.0 mL contains 16.0 mmol HCHO2 and 9.00 mmol NaCHO2. If 1.00 ml of 12 M HCl is added to this, what will be the resulting pH?
  2. CHEM REPOST...PLEASE CHEK!

    Posted by Kat on Monday, March 2, 2009 at 11:21am. A solution of volume 80.0 mL contains 16.0 mmol HCHO2 and 9.00 mmol NaCHO2. If 1.00 ml of 12 M HCl is added to this, what will be the resulting pH?
  3. Chemistry

    A solution contains 25 mmol of H3PO4 and 10. mmol of NaH2PO4. What volume of 2.0 M NaOH must be added to reach the second equivalence point of the titration of the H3PO4 with NaOH?
  4. Biochem

    What is the maximum amount of ethanol (in millimoles) that could theoretically be produced under the following conditions?
  5. Biochemistry

    In yeast, ethanol is produced from glucose under anaerobic conditions. What is the maximum amount of ethanol (in millimoles) that could theoretically be produced under the following conditions?
  6. Chemistry

    You are assigned the following amount of CoCl2. Volume of CoCl2 assigned and used 4.84 mL Concentration of CoCl2 1.39 M To this is added... Mass of charcoal 0.23 g Volume of 15.0 M ammonia 5.3 mL Mass of ammonium chloride 1.38 g The …
  7. Biochem

    In yeast, ethanol is produced from glucose under anaerobic conditions. What is the maximum amount of ethanol (in millimoles) that could theoretically be produced under the following conditions?
  8. BioChem

    In yeast, ethanol is produced from glucose under anaerobic conditions. What is the maximum amount of ethanol (in millimoles) that could theoretically be produced under the following conditions?
  9. Chemistry AP

    Hey Bob, What is the pH at the point during a titration when 20 mL of 0.200 M HCl has been added to 30 mL of 0.0500 M NH3 solution?
  10. CHE 2B

    A buffer solution of volume 50.0 mL contains 12.5 mmol HNO2 and 9.25 mmol KNO2. 1. What is the pH of this solution?

More Similar Questions