Please, I need help to do question 6 for the post-Lab questions
These is my values obtained in the laboratory :
volume of cyclohexanol = 7.39mL ; mass of cyclohexanol = 7.112 g
mass of cyclohexanone obtained = 1.535 g
Thymol blue = 3 drops
volume of Sodium Bisulfite = 1mL
volume NaOH used = 20mL
Continuation of the procedure
2- Place 0.0700 mol (How many mL would this be?) of cyclohexanol into the RB flask. To it add 6.00 mL of glacial acetic acid.
3- Turn on the stirrer slowly (not the heater!). Make sure the stir bar will not hit the tip of the thermometer. Add 82 mL of a 8.25 % w/w bleach solution (NaOCl (aq)) into the separatory funnel and slowly drip the bleach into the solution at such a rate that the temperature stays between 40-50 °C. The reaction is exothermic and you do not need to heat this reaction with the hot plate. However, do not allow the temperature to go below 40°C as the oxidation would be incomplete.
4- After all of the bleach has been added and the temperature starts to cool, stir for 15 minutes, then test the solution with starch iodide paper for excess bleach: This is done by first moistening the starch iodide paper with water, then bringing a drop of the solution (from the
Transcribed Image Text:44
EXPERIMENT 4: OXIDATION OF CYCLOHEXANOL TO CYCLOHEXANONE
8.
Place the distillate into a separatory funnel and add 50 mL of saturated NaCl solution to “salt
out" the organic phase. (Cyclohexanone is fairly soluble in water. The presence of salt will
make it less soluble.) Shake the mixture in the separatory funnel to dissolve the salt and
thoroughly mix the heterogeneous mixture. Next, carefully separate the top product layer from
the more voluminous bottom layer. This is best done by draining off the lower aqueous layer
and then transferring the remaining organic layer, with a Pasteur pipet, into a pre-weighed vial.
Determine the mass of the product and calculate the % yield.
9. To your product add a small amount of anhydrous MgSO4 or CaCl2 pellets as a drying agent.
Stir to mix and let it sit for about 5 minutes. Take one drop for an IR spectrum and take three
drops to measure the refractive index. Turn in the rest of your product in a labeled vial to your
instructor. Refer to page 23 to see what must be included on the label.
The IR spectrum must be fully analyzed: Label the major peaks with wavenumbers & explanations of
what they are due to (e.g. O-H stretch). Unreacted cyclohexanol, acetic acid and water would be the
major impurities. Take this into account as you analyze your IR spectrum. You can obtain IR spectra
of cyclohexanol and acetic acid from the Internet to include in your lab report for comparison. Be sure
to include in your lab report a discussion of and conclusions drawn from the comparison, and why you
measured the refractive index of your product.
Post-Lab Questions: (Remember to answer in full sentences & always explain your answer.)
1. You were to use 6.0 mL of glacial acetic acid. How many moles of acetic acid would that be?
Show your calculations carefully.
2. You were to use 82 mL of bleach. Assuming the bleach was indeed 8.25 % w/w NaOCI,
(equivalent to 1.24 M NaOC1), and there was sufficient acetic acid to convert all of it to HOCI,
how many moles of HOCI did you use? Show your calculations carefully.
3. Which was the limiting reactant in your oxidation of cyclohexanol? Explain clearly, showing
any calculations necessary to lead you to your conclusion.
4. As stated in the procedure, the most likely impurities are unreacted cyclohexanol, acetic acid
and water. How would you tell from the IR spectrum whether any or all of these impurities are
present in your final product? Explain carefully.
5. What purpose does the acetic acid serve in this oxidation reaction? Be specific.
6. Why was it important to neutralize the acetic acid before performing the steam distillation? Be
specific.
7. Write a chemical equation using structural formulas to show what happened to the acetic acid
when aqueous NaOH was added.
Transcribed Image Text:EXPERIMENT 4: OXIDATION OF CYCLOHEXANOL TO CYCLOHEXANONE
8. Place the distillate into a separatory funnel and add 50 mL of saturated NaCl solution to "salt
out" the organic phase. (Cyclohexanone is fairly soluble in water. The presence of salt will
make it less soluble.) Shake the mixture in the separatory funnel to dissolve the salt and
thoroughly mix the heterogeneous mixture. Next, carefully separate the top product layer from
the more voluminous bottom layer. This is best done by draining off the lower aqueous layer
and then transferring the remaining organic layer, with a Pasteur pipet, into a pre-weighed vial.
Determine the mass of the product and calculate the % yield.
9. To your product add a small amount of anhydrous MgSO4 or CaCl2 pellets as a drying agent.
Stir to mix and let it sit for about 5 minutes. Take one drop for an IR spectrum and take three
drops to measure the refractive index. Turn in the rest of your product in a labeled vial to your
instructor. Refer to page 23 to see what must be included on the label.
The IR spectrum must be fully analyzed: Label the major peaks with wavenumbers & explanations of
what they are due to (e.g. O-H stretch). Unreacted cyclohexanol, acetic acid and water would be the
major impurities. Take this into account as you analyze your IR spectrum. You can obtain IR spectra
of cyclohexanol and acetic acid from the Internet to include in your lab report for comparison. Be sure
to include in your lab report a discussion of and conclusions drawn from the comparison, and why you
measured the refractive index of your product.
Post-Lab Questions: (Remember to answer in full sentences & always explain your answer.)
1. You were to use 6.0 mL of glacial acetic acid. How many moles of acetic acid would that be?
Show your calculations carefully.
use to my bleach insted
. 2. You were to use 82 of bleach. Assuming the bleach was indeed 8.25 % w/w NaOCI,
(equivalent to 1.24 M NaOCI), and there was sufficient acetic acid to convert all of it to HOCI,
how many moles of HOCI did you use? Show your calculations carefully.
3. Which was the limiting reactant in your oxidation of cyclohexanol? Explain clearly, showing
any calculations necessary to lead you to your conclusion.
4. As stated in the procedure, the most likely impurities are unreacted cyclohexanol, acetic acid
and water. How would you tell from the IR spectrum whether any or all of these impurities are
present in your final product? Explain carefully.
5. What purpose does the acetic acid serve in this oxidation reaction? Be specific.
6. Why was it important to neutralize the acetic acid before performing the steam distillation? Be
specific.
7. Write a chemical equation using structural formulas to show what happened to the acetic acid
when aqueous NaOH was added.
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