When you prepare a buffer, it is recommended to use a weak acid whose pKa is close to the pH required for the buffer, why?

What is the general composition of a buffer and in your own words explain why it resists change in PH.

You wish to make a buffer of 500 mL at 0.1 M sodium phosphate at pH 6.5. If the molecular weight of NaH,PO4 and NazHPO4 are 121 g/mol and 143 g/mol, respectively, and the three pk, values for phosphoric acid are 2.14, 6.86, and 12.4, respectively, how many grams each of the two sodium phosphate salts must be dissolved to make 500 mL of a 0.1 M solution that buffers at pH 6.5?

A student wishes to make a buffer that has a pH of 4.65.  The student has HNO2 and NaNO2.  Nitrous Acid (HNO2) has a pKa of 3.40   Explain why the combination of these two compounds creates a buffer system.  What happens when ACID is added to the system? What happens when BASE is added to the system?

You need to produce a buffer solution that has a pH of 5.03. You already have a solution that contains 10. mmol (millimoles) of acetic acid. How many millimoles of acetate (the conjugate base of acetic acid) will you need to add to this solution? The pKa of acetic acid is 4.74. Express your answer numerically in millimoles.

4) a) Determine the mass (in grams) of sodium formate that must be added to 1.00 L of 0.180 M formic acid to prepare a buffer with a pH = 3.50. Assume there is no change in volume upon addition of the sodium formate. b) Write the predominant chemical reaction that occurs when 0.050 mol of HClO4 is added to 1.00 L of the buffer prepared in part a and calculate the pH of the solution.

19. A larger buffer capacity means that:       more buffer is needed to neutralize a strong base     the buffer is less resistant to changes in pH     more buffer is needed to neutralize a strong acid     the buffer is more resistant to changes in pH

ou need to produce a buffer solution that has a pH of 5.03. You already have a solution that contains 10. mmol (millimoles) of acetic acid. How many millimoles of acetate (the conjugate base of acetic acid) will you need to add to this solution? The pKa of acetic acid is 4.74.   Express your answer in millimoles.

Calculating the pH of a weak base titrated with a strong acid An analytical chemist is titrating 104.1 mL of a 0.1200M solution of propylamine (C,H,NH,) with a 0.2600M solution of HNO3. The p K, of propylamine is 3.46. Calculate the pH of the base solution after the chemist has added 53.1 mL of the HNO, solution to it. Note for advanced students: you may assume the final volume eguals the initial volume of the solution plus the volume of HNO, solution added. Round your answer to 2 decimal places. pH = Explanation Check O 2021 McGraw-Hill Education. All Rights Reserved. Terms of Use Privacy | Accessibility APR 23 MacBook Air O00 000 F4

A student makes 100.0 mL of a 0.100 M solution of HNO2.  What mass (in grams) of NaNO2  should the student add to the solution to make a buffer that buffers at a pH of 4.25. (Hint: use the Henderson-Hasselbalch equation to find the molarity, then find the number of moles required to achieve that concentration in 100.0 mL of solution.)