Homework Answers
4. Buffer capacity is defined as the ration of number of moles of acid [H+] or base [OH-] added per 1 liter of the solution to the change in pH of the solutionp.
the effective buffer capacity is from pka-1 to pka+1
and the pKa formic acid , the effective buffer capacity is 2.74 to 4.74( pKa of formic acid is 3.74)
A solution of formic/sodium acetate is expected to act as buffer between the pH range 2.74 to 4.74(
5. The pOH of basic buffer is given pOH = pkb + log(C5H5NHBr/C5H5N)
pKb of C5H5N = -logKb = -log(1.40*10^-9) = 8.85
[C5H5N] = 3.48 M
[C5H5NHBr] = 2.52 M
pOH = 8.85 + log(2.52/3.48)= 8.71
====> pH = 5.29
6.
after addition of NaOH
poH of buffer = pkb + log((C5H5NHBr+HCl)/(C5H5N-HCl))
pOH = 8.85+log((2.205+0.474)/(3.045-0.474) = 8.86
pH = 5.14
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4. Briefly explain the meaning of the term buffer capacity". A formic acid/sodium formate solution would...
I need help with #3, 4. Also, I am confused with #5 because both pH are...
I need help with #3, 4. Also, I am confused with #5
because both pH are the same.
Ka 1-7X10 4 3. In a titration between HCHO, and KOH, would the pH at the equivalence point be acidic, basic, or neutral? Briefly explain your answer. HCHO+KOH b) Which of the following acid-base indicators would be the best one to use in the titration? i) methyl orange, Ka = 104 ii) bromthymol blue, Ka = 10-7 iii) thymolphthalein, Ka= 10-10 4....
Calculate how to prepare 750 ml of 0.25 M sodium formate buffer at pH 4. Use...
Calculate how to prepare 750 ml of 0.25 M sodium formate buffer
at pH 4. Use your textbook to determine the molecular weight and
pKa of the acid and base. Calculate the grams of sodium formate and
number of milliliters of formic acid required. THEN using this
stock solution, calculate and describe how you would prepare 100 ml
of a 10 mM formate buffer, pH 3.5. By the way, what is the molarity
of formic acid?
with pH 7.6 and...
A chemist prepared an aqueous buffer containing both formic acid (HCOOH) and the formate anion. The...
A chemist prepared an aqueous buffer containing both formic acid (HCOOH) and the formate anion. The volume of the buffer is 100 mL ; with [HCOOH] = 0.110 mol L-1 and [HCOO- ] = 0.101 mol L-1 . The pKa of HCOOH = 3.74. What is the pH of this buffer? Write down the balanced chemical equation that describes the reaction of this buffer when an HCl solution is added. c) What is the resultant pH of this solution after...
A L.OOL buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The...
A L.OOL buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The...
A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
inn? 1. Formic acid, (K= 1.8x10) a WA, and sodium formate, its' CB, are mixed together...
inn? 1. Formic acid, (K= 1.8x10) a WA, and sodium formate, its' CB, are mixed together in a 250.0 mL volume of 0.350 M formic acid and 0.455 M sodium formate- to form a buffer solution. a. If 1.00 mL of 1.00 M HCI is added to 250.0 mL of DI water, what is the new pH? What is the pH if the 250.0 mL of solution was only 0.350 M HCOH (no formate)? b. c. What is the pH...
3. A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate....
3. A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
A buffer is composed of formic acid and its conjugate base, the formate ion. K for...
A buffer is composed of formic acid and its conjugate base, the formate ion. K for formic acid is 1.8 x 10. a What is the pH of a solution that has a formic acid concentration of 0.020 M and a sodium formate concentration of 0.055 M? pH
You combine 0.75 moles formate and 0.85 moles formic acid to make a buffer solution. The...
You combine 0.75 moles formate and 0.85 moles formic acid to make a buffer solution. The Ka of formic acid is 1.8xl0'4 what is the pH of the solution? With the same initial solution of 0.75 moles formate and 0.85 moles formic acid to make a buffer solution. The Ka of formic acid is 1.8xl0'4. You add 8g sodium hydroxide to this solution, what is the new pH? With the same initial solution of 0.75 moles formate and 0.85 moles...
how many grams of sodium formate must be dissolved in a 0.300 M solution of formic...
how many grams of sodium formate must be dissolved in a 0.300 M solution of formic acid to make 400.0 ml of a buffer solution with a pH=4.60?
I need help with #3, 4. Also, I am confused with #5
because both pH are the same.
Ka 1-7X10 4 3. In a titration between HCHO, and KOH, would the pH at the equivalence point be acidic, basic, or neutral? Briefly explain your answer. HCHO+KOH b) Which of the following acid-base indicators would be the best one to use in the titration? i) methyl orange, Ka = 104 ii) bromthymol blue, Ka = 10-7 iii) thymolphthalein, Ka= 10-10 4....
Calculate how to prepare 750 ml of 0.25 M sodium formate buffer
at pH 4. Use your textbook to determine the molecular weight and
pKa of the acid and base. Calculate the grams of sodium formate and
number of milliliters of formic acid required. THEN using this
stock solution, calculate and describe how you would prepare 100 ml
of a 10 mM formate buffer, pH 3.5. By the way, what is the molarity
of formic acid?
with pH 7.6 and...
A L.OOL buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
inn? 1. Formic acid, (K= 1.8x10) a WA, and sodium formate, its' CB, are mixed together in a 250.0 mL volume of 0.350 M formic acid and 0.455 M sodium formate- to form a buffer solution. a. If 1.00 mL of 1.00 M HCI is added to 250.0 mL of DI water, what is the new pH? What is the pH if the 250.0 mL of solution was only 0.350 M HCOH (no formate)? b. c. What is the pH...
3. A 1.00L buffer solution has the following concentrations: 1.50M formic acid and 1.25M sodium formate. The pK, for formic acid is 3.74. Determine the pH change of the buffer when 0.20moles of NaOH is added to the buffer. There is no change in the volume of the solution. (10 points)
A buffer is composed of formic acid and its conjugate base, the formate ion. K for formic acid is 1.8 x 10. a What is the pH of a solution that has a formic acid concentration of 0.020 M and a sodium formate concentration of 0.055 M? pH
You combine 0.75 moles formate and 0.85 moles formic acid to make a buffer solution. The Ka of formic acid is 1.8xl0'4 what is the pH of the solution? With the same initial solution of 0.75 moles formate and 0.85 moles formic acid to make a buffer solution. The Ka of formic acid is 1.8xl0'4. You add 8g sodium hydroxide to this solution, what is the new pH? With the same initial solution of 0.75 moles formate and 0.85 moles...
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