There are some topics in Chemistry that are very important from the point of view of the final examinations. The topic of determination of the boiling point of an organic compound is one such topic.
The determination of the boiling point of organic compounds is a topic that can also come up during the practice exam of students. This is why it is advised that students should pay special attention to this topic.
But what if a student missed the class during which the teacher was giving a lecture on the determination of the boiling point of organic compounds? If that is the case, then today is a lucky day for all students as we are going to discuss every major point that students need to learn about the determination of the boiling point of liquid organic compounds. However, before we get into that, students need to start with the basics.
Let’s begin with understanding the meaning of the boiling point. In the simplest terms, the boiling point of a substance can be defined as a particular temperature at which that substance would achieve a vapour pressure that is equal to the pressure around the liquid. This is also the temperature at which the liquid will change into a vapour.
To a large extent, the boiling point of a liquid will be dependent on the environmental pressure that is surrounding that liquid. This means that if a liquid is in a partial vacuum, then it would have a lower boiling point in comparison to the boiling point of the same liquid in atmospheric pressure.
Following that same logic, it can also be said that a liquid at a higher pressure will also have a higher boiling point in comparison to a liquid that is present at atmospheric pressure. To illustrate these points, an example can be taken. For example, if water boils at 1000 C at sea level, then it would boil at around 93.40 C at 1,905 meters altitude.
It is also important for students to note that different liquids will boil at different temperatures at a given pressure. These are all the basic points that students should know about the topic of boiling points.
In this section, students will be able to learn about the process that should be followed for the determination of the boiling point of liquid organic compounds. Students can also use this process to determine the boiling point of a given organic compound.
Students must be aware of the fact that organic chemistry is a branch of chemistry that mainly deals with the subject of composition and synthesis of organic chemical compounds. For students who are not familiar with the term, organic compounds are compounds that contain a carbon atom in their composition.
Now, let’s move on to discuss the process of identifying the boiling point of an organic compound. For ease of understanding, we will look at this entire process as a large experiment.
Aim: The aim of this experiment is to find out the boiling point of various organic compounds. To narrow things down, for the purpose of this experiment, two organic compounds called Benzene and Benzaldehyde are selected.
The Materials Required: To perform this process, an individual will require a stand with clamps, capillary tubes, tripod, thermometer, kerosene burner, Benzene, Benzaldehyde, fusion tube, and an aluminium block.
The Experimental Setup: It is rather difficult to explain the experimental setup without any visual aid. This is why an image of the ideal experiment setup is attached below.
(Image to be added soon)
The student should begin by taking the capillary tube and closing its end by holding the end in the flame. Rotating the tube for 2-3 minutes should do the trick
A few millilitres of benzene should be transferred to the fusion tube
Proceed to dip the capillary tube in the liquid in the fusion tube. Do not forget to keep the sealed end of the tube up
The tube should be inserted in one of the holes of the aluminium block. After that, a thermometer should also be inserted in the same block
After everything is placed inside the hole, one should make sure that the liquid is completely visible in the fusion tube
Put the aluminium block on the tripod
Use the kerosene burner to slowly heat the aluminium block
Make a note of the temperature as soon as regular streams of bubbles appear in the liquid present in the fusion tube
Begin the process similarly by closing one end of the capillary tube by holding that end in the flame and rotating it for 2-3 minutes
Place a few drops of benzaldehyde in the fusion tube
Keep in mind to put the sealed side up and dip the capillary tube in the benzaldehyde liquid filled in the fusion tube
Insert the tube and the thermometer into two separate holes made on the aluminium block
Make sure that you can observe the liquid present in the fusion tube clearly
Put the aluminium block on the tripod and start heating the block with the help of the kerosene burner
Make a note of the temperature as soon as a regular stream of bubbles appear on the liquid present inside the fusion tube
To date, we have looked at almost everything related to the process that one needs to follow to determine the boiling point of a given organic compound. However, the work of a student is still not done.
No task or experiment is complete or should even be allowed to carry out unless and until the students understand the precautions related to that experiment or procedure.
In this section, we will discuss some of the most prominent precautions students should take while finding out the boiling point of an organic compound. We have prepared a list of those precautions, and that list is mentioned below.
Make sure that the capillary tubes are completely sealed.
It is also important to ensure that the seal point of the capillary tubes should be within the liquid.
Use proper lab equipment and follow all safety precautions.
Did you know that the element with the lowest boiling point in the world is helium? Further, the boiling points of tungsten and rhenium are said to exceed 5000 K, but nobody has been able to find out the exact boiling point as it is difficult to measure extreme temperatures.
Also, if a student has carried out the experience that was mentioned above, then he or she would have observed that the boiling point of benzene is around 780C and the boiling point of benzaldehyde is 1780 C.
1. What is the boiling point of water?
The boiling point of water is 1000 C
2. What is the boiling point of benzene?
The boiling point of benzene is 780 C
3. What is the boiling point of benzaldehyde?
The boiling point of benzaldehyde is 1780 C
4. Explain why carboxylic acids have a higher boiling point than hydrocarbons
Carboxylic acids have a higher boiling point as they have the capacity to form hydrogen bonds. These bonds provide these molecules with extra stability that further allows these molecules to form additional bonds by employing dispersion forces.
5. What would be the boiling point of water at higher altitudes?
At higher altitudes, the boiling point would be less than 1000 C.