Question

In: Chemistry

Design a buffer solution from acids listed in the table. You need to prepare 1.50 L...

Design a buffer solution from acids listed in the table.

You need to prepare 1.50 L of buffer with pH 4.30. Show your calculations for molar calculations of acid and conjugate base, then fill in the answer table below.

Acid	Formula (H is the acidic hydrogen)	pKa
Acetic acid	CH₃CO₂H	4.756
Benzoic acid	C₆H₅CO₂H	4.202
Formic acid	HCO₂H	3.745
Hydrazoic acid	HN₃	4.600
Hydrofluoric acid	HF	3.170
Lactic acid	HC₃H₅O₃	3.860
Trifluoroacetic acid	C₂HF₃O₂H	2.523

Expert Solution

Benzoic acid is chosen, since its pKa is closest to the required pH.

The molar ratio is calculated:

n A- / n HA = 10 ^ (pH - pKa) = 10 ^ (4.30 - 4,202) = 1.25

It has:

i) n A- - 1.25 * n HA = 0

ii) n A- + n HA = M * V = 0.1 M * 1.5 L = 0.15 mol

The system of equations between i and ii is solved:

n A- = 0.083 mol

n HA = 0.067 mol

The mass of benzoic acid and sodium benzoate required is calculated:

m Acid = n HA * MM = 0.067 mol * 122.12 g / mol = 8.18 g

m Benzoate = 0.083 * 144.11 = 11.96 g

The above masses are diluted in a volume of distilled water of 1.5 L.

If you liked the answer, please rate it positively, you would help me a lot, thanks.

queen_honey_blossom answered 3 years ago

You are asked to prepare a pH=4.00 buffer starting from 1.50 L of 0.0200M solution of...

You are asked to prepare a pH=4.00 buffer starting from 1.50 L of 0.0200M solution of benzoic acid (C6H5COOH) and an excess of sodium benzoate (C6H5COONa). Part A What is the pH of the benzoic acid solution prior to adding sodium benzoate? Express your answer using three significant figures. Part B How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the sodium benzoate is added. Express your answer...

1. Describe how you would prepare 1.50 L of a 0.500 M phosphate buffer with a...

1. Describe how you would prepare 1.50 L of a 0.500 M phosphate buffer with a pH of 7.5. (show work) 2. If 5.00 mL of 0.150 M HCl is added to 0.750 L of your buffer from (1), what will the new ph be? (show work) 3. If 10.00 mL of 1.50 M NaOH is added to 0.750 L of your buffer from (1), what will the new ph be? (show work)

if you need to prepare a buffer solution at pH 7.4 from a weak base/ conjugate...

if you need to prepare a buffer solution at pH 7.4 from a weak base/ conjugate acid buffer system which buffer system would you pick and why?

A 1.50 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate...

A 1.50 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the solution after the addition of 0.0500 moles of solid NaOH. Assume no volume change upon the addition of base. The Ka for HF is 3.5 × 10-4.

Your boss asks you to prepare approximately 1 L of a 0.10 M buffer solution of...

Your boss asks you to prepare approximately 1 L of a 0.10 M buffer solution of acetic acid (Ka = 1.8x10^(-5)). As a first step, you add 0.10 mol of acetic acid to 900 mL of water. You select 6.0 M NaOH as your base. How many milliliters base would you add? Edit: The question does not specify a pH for the buffer. Is there any way to solve without pH?

You need to prepare 100.0 mL of a pH = 4.00 buffer solution using 0.100 M...

You need to prepare 100.0 mL of a pH = 4.00 buffer solution using 0.100 M benzoic acid (pKa = 4.20) and 0.200 M sodium benzoate. How much of each solution should be mixed to prepare this buffer?

BUFFER PROBLEMS You are asked to prepare 1.2 L of a 0.05 M tris buffer at...

BUFFER PROBLEMS You are asked to prepare 1.2 L of a 0.05 M tris buffer at pH= 7.8. You start with the conjugate base form of tris (121 g/mol). How many grams of tris must you weigh out? How many mL of 6 M HCl (a strong acid) must you add to reach pH=7.8? The pKa for tris is 8.1.

How to prepare a buffer solution? We will be assigned a pH. We need to write...

How to prepare a buffer solution? We will be assigned a pH. We need to write a procedure in order to prepare 100 mL of a buffer solution of that pH from two solids. The procedure should clearly identify which glassware and chemicals used to prepare the solution. Assume you will use the sodium salt of the conjugate base to prepare the solution.

Suppose you need to prepare 1.0 L of Stock solution which must have a concentration of...

Suppose you need to prepare 1.0 L of Stock solution which must have a concentration of 150 mg N/L. You start with solid Potassium Nitrate, KNO3 . A. How many moles of Nitrogen should 1.0 L of Stock solution contain? B. How many moles of KNO3 should 1.0 L of stock solution contain? C. How many grams of KNO3 will you have to weigh out to prepare 1.0 L of stock solution? (Show ALL work!) (Reminder: the concentration of stock...

You need to prepare 100.0 mL of a pH=4.00 buffer solution using 0.100 M benzoic acid...

You need to prepare 100.0 mL of a pH=4.00 buffer solution using 0.100 M benzoic acid (pKa = 4.20) and 0.120 M sodium benzoate. How much of this solution should be mixed to prepare this buffer? Sum of volumes must equal 100mL. Please explain clearly and show work! Thank you :)