Distillation is a significant commercial technique that is used to purify a wide range of materials. It is the procedure of selective boiling and condensation to separate the components or compounds from a liquid combination.
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Distillation can produce an almost complete separation (almost pure components) or a partial separation (increased concentration of selected components in the mixture). The technique uses changes in the relative volatility of the mixture’s components in each situation. Distillation is a unit operation of virtually universal importance in industrial applications, although it is a physical separation process, not a chemical reaction.
Distillation Chemistry Questions with Solutions
Q1: Porcelain pieces are put into the distillation flask to avoid ____________
a) Overheating
b) Bumping of the solution
c) Uniform boiling
d) None of the mentioned options
Answer: b) Bumping of the solution
Explanation: To prevent the solution from bumping due to uneven heating, porcelain pieces are placed in the distillation flask.
Q2: What are the two processes in distillation?
a) Distilling and condensation reflux
b) Distilling and freezing
c) Freezing and condensation reflux
d) Only condensation reflux
Answer: a) Distilling and condensation reflux
Explanation: Distillation is a two-step process that includes distillation and condensation reflux. The gas-liquid two-phase flow over the countercurrent contact is commonly carried out in a distillation column.
Q3: How aniline and chloroform can be separated?
a) Sublimation
b) Condensation
c) Distillation
d) Evaporation
Answer: c) Distillation
Explanation: The distillation technique can be used to separate aniline and chloroform. The toxic organic molecule aniline has the formula C6H5NH2. The organic compound chloroform has the formula CHCl3. It’s a colourless, sweet-smelling, thick liquid that’s used as a precursor to PTFE and refrigerants on a huge scale.
Q4: Which of the following is not separated through the distillation process?
a) Acetone and water
b) Milk and water
c) Impurities in Sea water
d) Aniline and chloroform.
Answer: c) Impurities in Sea water
Explanation: The distillation technique does not separate milk from water. A distillation procedure can separate all of the other options.
Q5: The process of distillation is used for the liquids having ____________
a) Sufficient difference in their solubility
b) Sufficient difference in their melting point
c) Sufficient difference in their boiling point
d) None of the mentioned
Answer: c) Sufficient difference in their boiling point
Explanation: The distillation method is employed for liquids with a significant difference in boiling points. Distillation also allows you to separate the components of air.
Q6: Which salt is obtained as a result of the chemical reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH)? Which method will you use to separate it from the solution?
Answer:
The chemical reaction between HCl and NaOH gives rise to common salt (NaCl). The following is a representation of the chemical reaction:
HCl + NaOH → NaCl + H2O.
The salt is separated from the solution using the distillation process.
Q7: Draw a labeled diagram showing the process of distillation.
Answer:
The distillation process is depicted in the diagram below.
Q8: Match the following:
Answer:
(a) Melting point – 4. Change of state from solid to liquid.
(b) Boiling point – 3. Change of state of a liquid into a gas.
(c) Fractional distillation – 2. Obtaining diesel from crude oil
(d) Distillation – 1. Separating common salt and water from their mixture.
Q9: Answer the following questions.
- What will you do to find out the boiling point of water?
- What changes do you see in the appearance of a candle after you have lit it?
- Can a solid and a solvent be separated from their solution by distillation?
Answer:
- To determine the boiling point of water, we will use the following apparatus:
Experiment: We’ll put water in a flask with a round bottom and a single holed rubber stopper. We’ll put a thermometer in the hole and start heating the flask by placing it on iron gauze on a tripod stand.
Observation: The increase in temperature in the thermometer will be observed. When the mercury within the thermometer reaches 100°C., water begins to boil, and the temperature falls.
Conclusion: The boiling point of water is defined as the temperature at which the temperature stops rising and the water begins to boil. As a result of the experiment, the boiling point of water is 100°C.
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- When we light the candle, the following changes occur
(i) State change: The candle’s wax melts and then vaporises to generate wax vapours.
(ii) Combustion: Heat and flame are produced when wax vapors burn.
- Yes, distillation can separate components of a solution made up of a dissolved nonvolatile solid (solute) and a liquid (solvent).
Q10: What is the difference between distillation and fractional distillation?
Answer:
The following table summarises the differences between distillation and fractional distillation:
Q11: Mention the various uses of Distillation.
Answer:
Some of the uses of Distillation are as follows:
- It can be used in a laboratory to do experiments. The results aren’t immediately utilised, although they can help with chemical and medicinal research.
- Distillation may remove numerous pollutants from water, making it beneficial for purification. Desalination plants use the seawater distillation process to obtain pure water. When making infant food, parents use distilled water.
- Distilling ferment material (a mixture of fruit and animal components) creates ethyl alcohol, which is used to make alcoholic beverages.
- When crude oil is distilled, various compounds such as gasoline, wax, fuel oil, lubricating oil, and other petrochemical products separate at different boiling points.
- Distillation produces the perfumes we use today. We extract essential oil and aroma from many plants and herbs using this method. Simple distillation is not used because plants begin to disintegrate at higher temperatures. As a result, steam distillation is beneficial.
- Food flavour is created by steam distillation. Citrus oils, for example.
- Acetone and methyl alcohol are separated via fractional distillation.
- Oxygen, nitrogen, carbon dioxide, argon, and other gases are found in the air. Cryogenic distillation can be used to remove these gases.
- The sugarcane industry uses vacuum distillation to concentrate sugarcane juice.
Q12: Fractional distillation can be used to separate miscible liquids having a boiling point difference of less than 25 K. What part of the fractional distillation equipment makes it efficient and superior to a normal distillation process? Use a diagram to explain.
Answer:
Fractional Distillation of Miscible Liquids
- A fractionating column improves the efficiency of fractional distillation over simple distillation by increasing the possibility of liquid condensation.
- A fractionating column with glass beads or glass helices provides a vast surface area for the vapours to collide and lose energy, allowing them to be quickly condensed and distilled.
- Fractional distillation efficiency could be improved by increasing the length of the fractionating column.
Q13: Which tubes in Fig. 2.1 (a) and (b) will be more effective as a condenser in the distillation apparatus?
Answer:
As a condenser in the distillation equipment, tube (a) will be more effective. The presence of marbles enhances the surface area of the vapours’ contact area. This gives the vapours more time to condense, making the first column more effective than the second column without marbles.
Q14: Give an example of each mixture having the following features. Suggest a suitable method to separate the components of these mixtures
a) A volatile and a non-volatile component.
b) Two volatile components with appreciable differences in their boiling point.
c) Two immiscible liquids.
d) Two or more coloured constituents soluble in some solvents.
Answer:
(a) Example: Mixture of acetone and water.
A mixture of volatile and non-volatile components can be separated by simple distillation.
(b) Example: Mixture of kerosene and petrol.
Simple distillation can be used to separate two volatile components with significant boiling point differences.
(c) Example: Mixture of mustard oil and water.
Separating funnel is used to separate a mixture of immiscible liquids.
(d) Example: A mixture of different pigments from an extract of flower petals.
Two different compounds present in the same solution can be separated using the chromatography method.
Q15: Briefly describe Vacuum Distillation.
Answer:
- Vacuum distillation is ideal for separating mixtures of liquids with extremely high boiling points.
- Heating these chemicals at high temperatures is an ineffective technique for boiling them. As a result, the pressure in the environment is reduced.
- Because the pressure is reduced, the component can boil at lower temperatures. The component is transformed into a vapour when its vapour pressure equals the ambient pressure.
- The fumes are then condensed, and the distillate is collected. High-purity samples of chemicals that degrade at high temperatures are also obtained using the vacuum distillation method.
Practise Questions on Distillation
Q1: What are the basic methods of distillation?
a) Fractional distillation and simple distillation
b) Steam distillation and destructive distillation
c) Steam distillation, simple distillation, and gas distillation
d) Fractional distillation, destructive distillation, and simple distillation
Q2: Define the following terms.
(a) Melting point
(b) Boiling point
(c) Distillation.
Q3: Give scientific reasons.
(a) A condenser has two taps.
(b) At dawn, in winter, we see dewdrops on the leaves of trees
Q4: Salt is dissolved in seawater. You’re probably aware that you can distill pure water from seawater. This approach, however, is not used to obtain drinking water from seawater. What do you believe the reason is?
Q5: Two water samples, labeled ‘A’ and ‘B,’ are given to you. Sample “A” boils at 100°C, while sample “B” boils at 102°C. Which water sample will not freeze at 0°C? Comment.
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Vacuum distillation...experiment results and silly question.
Post
by nzhuhu » Tue Mar 10, 12:11 am
Dear every one,
I am trying vacuum distillation technic. My kit is glass vacuum rated ( borisilicate 3.3 ) with dry vacuum pump, chiller i use ice with water pump ( usually run at 15 degree celcius through condenser ). I also place empty pot in middle of vacuum line ( connect from vacuum pump to distill kit ) to secure the vacuum also stop the vacuum pump from running all the time.
My fist test with grapefuit ( white meat ) and lemongrass. Here is my parameter:
Chopping all material to 3mm cubic put them in the pot together with water ( submerging material in water ).
Turn on vacuum pump to sucking all air in side the distill system and the empty pot also. Reaching the requiment: for negative gauge -26inHg/-88kPA/-12.79PSIG/87% vacuumed air , for positive gauge 3.8inHg/13.17kPA...just for easy convert for your convenient.
Now i start the heating, i set it heat up to 63 degree celcius and i get bubble....at 70 degree i get heavy boiling. I let it stay at 63 degree
Every 1hr the vacuum is moving up so i have to vacuum again for 3 mins, after that degree of the pot is droping down from 59 to 6p degree, the heat will back up to 63 in 10 mins.
Yes i get liquid coming out at collecting pot with the smell almost the same as raw yeast of the fruit but there is no oil even i am using reparate funnel. I suspect i collect hydrosol water, please correct me. Here i am getting confuse, do i have to make the water going into heavy boiling phase ? Or i must have to consider the boiling point of the oil which i plan to extract ?
Please do teach me. Thank you very much.
Re: Vacuum distillation...experiment results and silly question.
Post
by Windswept » Tue Mar 10, 9:51 am
So, my understanding of this kind of separation is that running the still will move alcohol, then water into the collection flask from the boiling flask until you are left with the hydrosol (in the boiling flask).
If I didn't learn the hard way, I wouldn't learn at all!
Re: Vacuum distillation...experiment results and silly question.
Post
by OtisT » Tue Mar 10, 8:01 pm
Nzhuhu,
I have a guess as to why you are getting hydrosol but not essential oils. I think if you used a high proof alcohol rather than water, you would see a lot more oil output. Hydrosol contains plant material that is dissolvable in water. Oil does not dissolve in water as far as I understand it.
This is just a guess. I have never tried extracting essential oil with a water only distillation. I have done a handful of essential oil distillations in a vacuum still using a high proof neutral spirit and I never had problems getting some oil with my hydrosol.
PS. You should use a very good neutral for this. Something with no smells or flavors. If you don’t make your own neutral or a clean vodka, I recommend you buy a nice triple distilled vodka. There are several old threads on HD where folks shared what they consider the cleanest commercial vodkas. Don’t use everclear or similar products.
Otis
Otis’ Pot and Thumper, Dimroth Condenser:
Pot-n-Thumper/Dimroth
Learning to Toast:
Toasting Wood
Polishing Spirits with Fruitwood:
Fruitwood
Badmotivator’s Barrels:
Badmo Barrels
Re: Vacuum distillation...experiment results and silly question.
Post
by nzhuhu » Thu Mar 12, 1:44 pm
Thank you Windswept and OtisT,
You might misunderstand Windswept, i am trying to extract oil essential from fruit such as grapefruit but no success, i only collect hydrosol water no oil on top of it.
Thank you OtisT, i really do not want to use any ethanol or chemical even medicine grade. I really hope to get oil from low boiling point of water so it will not harm flavour. I still have not figuring out what is wrong, i wish there is some step by step or any Study of this vacuum distillation technic. Keep looking then.
Best regards.
Re: Vacuum distillation...experiment results and silly question.
Post
by manu de hanoi » Fri Nov 27, 7:54 am
what was the volume of water and weight of skins/lemongrass ?
Re: Vacuum distillation...experiment results and silly question.
Post
by tiramisu » Fri Nov 27, 12:52 pm
Ummm, water is a solvent, alcohol is a solvent. There are many solvents. You need to use the solvent suitable for the thing you are trying to extract. Given that you are using vacuum to reduce the heat required it would be seem reasonable to use a more appropriate solvent in order to achieve a more effective extraction. The response that you do not want to use chemicals shows a misunderstanding of the process. Water is as much a chemical as is alcohol. The question is what is most appropriate for oil extraction. You might consider bho or propane extraction as another alternative. It is not clear whether you are trying to achieve separation of turpenes but if so you may want to look to short path or film distillation.
My untrained thought would be to use a soxhlet to extract the oils with minimal alcohol and then use a short path distillation set up and play with separation of the turpenes so that you could create flavor recipes.
Re: Vacuum distillation...experiment results and silly question.
Post
by JesseMarques » Fri Nov 27, 4:30 pm
actually water is suitable for extracting oil, when you steam distill plant material water vapor can carry molecules with higher BP. The OP seems to know that, as it is wanted to get an hidrosol water with oil on top, but he doesn't have it
Re: Vacuum distillation...experiment results and silly question.
Post
by nzhuhu » Mon Apr 04, 5:35 am
Thank you everyone. I wish you all happy and healthy after this Covid pandemic...More than a year i can get back to my project. I did try 1 experiment during lock down and jobless: using real essential oil mixed with water then run Vacuum Distillation, low heat, high vacuum. The oil appeared in the collecting flask + water or hydrosol. Then i put the project on hold for 1 year. Last week i used ethanol mixed with materials, got the solution ( suppose ethanol + oil + wax +.... ). And I mixed water with that Ethanol Solution above...inside the mixing solution it formed a resin ( slime type, stick to dry hand but not to wet hand ). I take a small slime or resin and let it dry at room temperature, the resin getting harder and solid. I wonder what happens inside the ethanol solution when mixed with water. Is it possible to put this slime or resin in water and use vacuum distillation to extract the essential oil ? Thank you very much
Re: Vacuum distillation...experiment results and silly question.
Post
by Aluda » Sat Feb 25, 9:10 am
Here are some pictures of the sophisticated essential oil extraction equipment. Since the oil content is negligible. A cunning double condenser was made, the first one can be washed by supplying pure solvent vapor, the second condenser, also known as a glass vial, a place for selecting the final product, a storage condenser. To protect the glass vial from bursting, external pressure is applied to the vial during pressurized operation. A device for working with solvents under pressure, such as butane, refrigerant, freon, lighter gas.
And here is a real ethereal little Crimean Lavender. Not with this complex apparatus, but with ordinary water vapor.
Re: Vacuum distillation...experiment results and silly question.
Post
by Spirit » Fri Mar 31, 11:50 am
OtisT wrote: ↑Tue Mar 10, 8:01 pm
Nzhuhu,
I have a guess as to why you are getting hydrosol but not essential oils. I think if you used a high proof alcohol rather than water, you would see a lot more oil output. Hydrosol contains plant material that is dissolvable in water. Oil does not dissolve in water as far as I understand it.
This is just a guess. I have never tried extracting essential oil with a water only distillation. I have done a handful of essential oil distillations in a vacuum still using a high proof neutral spirit and I never had problems getting some oil with my hydrosol.
PS. You should use a very good neutral for this. Something with no smells or flavors. If you don’t make your own neutral or a clean vodka, I recommend you buy a nice triple distilled vodka. There are several old threads on HD where folks shared what they consider the cleanest commercial vodkas. Don’t use everclear or similar products.
Otis
Why no Everclear?
Re: Vacuum distillation...experiment results and silly question.
Post
by OtisT » Fri Mar 31, 3:15 pm
Contact us to discuss your requirements of Oil Distillation Plant. Our experienced sales team can help you identify the options that best suit your needs.
Spirit wrote: ↑Fri Mar 31, 11:50 am
OtisT wrote: ↑Tue Mar 10, 8:01 pm
Nzhuhu,
I have a guess as to why you are getting hydrosol but not essential oils. I think if you used a high proof alcohol rather than water, you would see a lot more oil output. Hydrosol contains plant material that is dissolvable in water. Oil does not dissolve in water as far as I understand it.
This is just a guess. I have never tried extracting essential oil with a water only distillation. I have done a handful of essential oil distillations in a vacuum still using a high proof neutral spirit and I never had problems getting some oil with my hydrosol.
PS. You should use a very good neutral for this. Something with no smells or flavors. If you don’t make your own neutral or a clean vodka, I recommend you buy a nice triple distilled vodka. There are several old threads on HD where folks shared what they consider the cleanest commercial vodkas. Don’t use everclear or similar products.
Otis
Why no Everclear?
In my opinion Everclear is not a clean neutral. It appears to not be cut (well) and I can smell nasty heads in it. Maybe tails too, but I don’t recall exactly because it’s been a while since I have smelled that stuff. Next to a clean neutral, the difference is night and day.
Otis’ Pot and Thumper, Dimroth Condenser:
Pot-n-Thumper/Dimroth
Learning to Toast:
Toasting Wood
Polishing Spirits with Fruitwood:
Fruitwood
Badmotivator’s Barrels:
Badmo Barrels