Pre-Lab Questions: 1. Draw a schematic of the setup that you will use for the si

Question

Pre-Lab Questions:
1. Draw a schematic of the setup that you will use for the simple distillation. Be sure to indicate all of the clamp and clip locations.
2. How would you correct for temperature if your refractive index reading was taken at 22 degrees C as opposed to 20 degrees C?
3. A student attempts to separate a sample of cyclohexane and ethylbenzene by distillation. After the distillation the student obtains an 20 of 1.4355 for what should be pure cyclohexane with a volume of 23.5 mL. Did the student obtain pure cyclohexane? If not, what volume of ethylbenzene is present in the distilled cyclohexane?

i need help with questions #2 and #3.
below I have typed the lab all out as I couldn't get photos to work on my phone.

Distillation:
Introduction
Distillation is a common laboratory technique used to purify liquids. In this experiment you will be working with partners and perform a simple distillation to separate a mixture of solvents that contains a high boiling solvent (toluene or ethylbenzene) from a low boiling solvent (hexane, heptane, or cyclohexane). Be sure to have the boiling points for the possible chemicals. You will be given the identity of the high boiling solvent but it is your job to determine the identity of the low boiling solvent based on the observed boiling point during the distillation.
Pay special attention to the discussion on clipping a distillation setup. We use the Keck clips. One part that Padías does not mention is what happens when you do not correctly line up the skinny part and fat part of a blue clip to the skinny part and fat part of our glassware: they crack and then they will never work again. Please do not crack our Keck clips (a much more common issue than melting the Keck clips!).
The Padías chapter on distillation is really really long. Luckily, we will not be doing a vacuum distillation or a steam distillation, so you can disregard the parts on those techniques. It may also be a good idea to use aluminum foil on your setup to help it heat up faster.
The purity of your solvents will be assessed using refractometry. Be sure to read Padías to understand how to use the refractometer. The value of ( 20) can be approximated as the weighted average of the refractive indices of the individual components. For a hexane/heptane mixture
20( ) = 20( ) + 20( )
where V stands for volume fractions. For instance a 1:1 mixture of hexane/heptane would have V = 0.5 for hexane and heptane. If the volume fractions are unknown but the 20 of the mixture is known the volume fractions can be calculated by treating one volume as x and the other as (1-x). Solving for x will give the volume fraction of one of the compounds. Simply multiplying the volume fraction by the total volume obtained will give the volume of the individual compound in the mixture. 20( ) = 20( ) + (1 ) 20( )
Materials (and Refractive Indices, 20) cyclohexane (1.4266) toluene (1.497)
ethylbenzene (1.495) hexane (1.375) heptane (1.387)
Procedure
Each group will select one of the five mixtures and will perform a simple distillation on that mixture. Start by setting up the simple distillation as discussed in Padías. You will need to use some sand to make better contact between the thermowell and the round bottom flask. (“Some” sand = about enough to cover half of the flask). Use 18 mL of the unknown mixture for the distillation. Remember to use a boiling stone.
For your receiving flask, use a small 10 mL graduated cylinder. Record temperature readings for every 0.5 mL of liquid you collect. You will be collecting the lower boiling solvent in the graduated cylinder and leaving behind the higher boiling solvent in the still pot. Once the solvents have cooled enough to handle determine the total volume obtained of the low boiling solvent and the high boiling solvent that remains in the still pot. Obtain the refractive indices of the low and high boiling solvent and then clean- up. Dispose of all organic solvents in the organic waste and clean out your distillation apparatus. Return all items that were taken from the hood or cart.

Explanation / Answer

2) Actually the refractive indx value decreases by 0.00045 ± 0.0001 for every 1degree celsius reading. and so for 20 degree celsius one add the above approximation to the value obtained at 22 degrees cel.

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