Please solve question 2 EXPERIMENT 8: BUFFERS Maintaining the pH of a solution c
ID: 1039187 • Letter: P
Question
Please solve question 2 EXPERIMENT 8: BUFFERS Maintaining the pH of a solution can be very important, especially in bio- logical systems. Practically all biological molecules require a particular pH in order to function properly. Thus the pH of the fluids found in living organisms must be maintained at rather specific values or the chemical re- actions necessary to maintain life will not occur as they should. Blood is a very good example of this. Normally human blood has a pH of 7.1. Should the pH rise above 7.3 or fall below 6.9, it will no longer be able to carry sufficient oxygen and other necessary molecules to sustain life. To ensure its phi remains at 7.1, blood contains a very complex system of acid-base buffers. These buffers counteract the acids and bases generated by the vari- ous chemical reactions that occur in the blood, thereby maintaining the correct pH. 51 OBJECTIVES Educational Objectives explain how an acid/base buffer works and . prepare a solution buffered to a specific pH value. Experimental Objectives riment will be able to: A student who performs this experiment is asked to: prepare a buffer solution and investigate its ability to buffer pH change. prepare a buffer solution having a specific pH value, and demonstrate the ability of the buffer solution to resist pH change.Explanation / Answer
Hi we will prepare a buffer that 1:1 molar ratio of HOAc:NaOAc
[0.1M HOAc + 0.1M NaOAc] ------- combination is a buffer.
HOAc is acetic acid, is a liquid weak acid. Our target concentration is 0.1 M (M stands for molarity = moles / liter)
acetic acid molar mass = 60.05 g/mol
Mass of acetic acid required to prepare 100 mL of 0.1M concentration = [molarity x molar mass of acetic acid] x [volume in mL /1000]
Mass of acetic acid required to prepare 100 mL of 0.1M concentration = [0.1M x 60.05 g/mol] x [100 mL/1000]
Mass of acetic acid required to prepare 100 mL of 0.1M concentration = 0.6005 g, but acetic acid exists as liquid, hence we need to convert mass in grams to volume in mL considering its density.
acetic acid density = 1.049 g/mL, density = mass / volume
volume = mass / density = 0.6005 g / 1.049 g/mL = 0.57 mL
volume of acetic acid has to be taken = 0.57 mL
{Sodium acetate) NaOAc molar mass = 82.0343 g/mol
Mass of sodium acetate required to prepare 100 mL of 0.1M concentration = [0.1M x 82.0343 g/mol] x [100 mL/1000]
Mass of sodium acetate required to prepare 100 mL of 0.1M concentration = 0.82 g
Procedure:
1. Take clean and dry 100 mL graduated volumetric flask with stopper
2. add 0.57 mL of acetic acid to above flask by using graduated 1 mL glass syringe.
3. Now also add 0.82 g of NaOAc to above flask.
4. add pure distilled water to above flask upto the 100 mL mark.
5. Put the glass lid. Now shake well and gently the mixture to get clear homogeneous solution.
6. Done! we prepared HOAc-NaOAc buffer solution. That's it.
Hope this helped you!
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