Thermodynamics is a branch of physics that explains the properties of heat and reactions of eat energy with different chemicals. As a part of this, here we are going to understand the release in heat due to the interaction between acetone and chloroform, which can be termed as enthalpy change. Let's see the experiment's detailed explanation to evaluate the enthalpy change during interaction between acetone and chloroform.
Enthalpy Change Definition
The enthalpy change definition can be explained in several ways. We can explain the sum of both internal energy and the product of volume and pressure in simple terms.
H= E+ PV
Where H = Enthalpy change
E = Internal Energy
P = Pressure
V = Volume
Aim
To evaluate the enthalpy change during the interaction between acetone and chloroform.
Explanation
According to Raoult Law, when we mix two liquid pairs, they will interact with each other and behave ideally. In contrast to the Raoult law, the interaction of acetone and chloroform showed non-ideal behaviour due to the formation of hydrogen bonds and released in thermal energy. This deviation against the Raoult Law encouraged several scientists to investigate this. Hence, some theoretical and experimental studies have taken place.
The respective chemical equation is as follows-
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The formation of hydrogen bonds during acetone and chloroform interaction reduces the escaping tendency among the acetone and chloroform. It leads to breaking the expectations on released vapour pressure. Besides this, both molecules hold weak van der Waal forces at their pure state. At this moment, we can observe the enthalpy change during interaction with the formation of hydrogen bonds. Hence the enthalpy change of reaction was observed for a specific amount.
Required Materials to Perform Experiment
To determine the enthalpy change during the interaction between acetone and chloroform, we need to perform an experiment that requires the following list of materials.
Boiling tube
Glass rod
Cotton wool
Beaker
Chloroform
Measuring cylinder
Piece of cardboard
Thermometer
Acetone
Step by Step Procedure
Let see the step-by-step procedure to find out the enthalpy change during the interaction between acetone and chloroform.
First, we need to calculate the water level, whether it should be equivalent to the level of the beaker or calorimeter.
Take equal amounts of both acetone and chloroform; let's say 50 mL of the solution in two different beakers separately.
Record the temperature of both the solutions initially to find out the enthalpy change at the end of the experiment.
Now we need to transfer the specific amount of chloroform from the beaker to the insulated boiling tube. Use a measuring cylinder to measure exactly 0.1 moles of chloroform.
And do the same thing for acetone also using a clean measuring cylinder. We should not use the same cylinder, in which we have measured the chloroform.
Now transfer 0.1 moles of acetone which we have connected into the chloroform in an insulated boiling tube.
Stir the mixture of acetone and chloroform.
Start recording the temperature.
Now calculate the rise in temperature using the observations.
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Observations
Calculations
From the observations, we can calculate and find the enthalpy change of formation. It is measured in Joules.
The formula for enthalpy change is,
= W*4.2*(t1-t2)+[100*1.499*s1 +100 *0.787*s2](t1-t2) joules
= ______ joules.
Hence it is the result obtained when we mixed 100ml of both acetone and chloroform to find out the enthalpy change during the interaction.
Precautions to be Taken
For every experiment, you want to take necessary precautions to avoid unnecessary risks and adverse effects of chemicals. Similarly, for this experiment, we also need to take some precautions. They are listed below-
We should measure the quantity of acetone and chloroform carefully to get the exact value.
One should be more attentive and careful while steering the mixture of acetone and chloroform.
Using cotton for thermal insulation is always suggestible.
Use a graduated thermometer and record the values of changing temperature carefully.
Approach the doctor immediately if any chemical splits on the skin accidentally.
Use gloves, glasses, masks, etc., to protect sense organs.
Conclusion
Hence, the experiment has proved that 1 mole of acetone and chloroform will show non-ideal behaviour, resulting in enthalpy change during the interaction. One should follow all the precautions while experimenting with yielding good results.
FAQs on Enthalpy Change During The Interaction Between Acetone and Chloroform
1. What happens when acetone and chloroform are mixed together?
When acetone and chloroform are mixed, they form a non-ideal solution that releases heat, making it an exothermic process. This interaction leads to a decrease in the total volume of the solution and results in a negative deviation from Raoult's Law, meaning the solution's vapour pressure is lower than expected for an ideal solution.
2. Why is the enthalpy change negative for the acetone and chloroform interaction?
The enthalpy change (ΔHmix) is negative because the intermolecular forces of attraction formed in the solution are stronger than those in the pure liquids. A new, strong hydrogen bond forms between the hydrogen atom of chloroform (CHCl₃) and the oxygen atom of acetone (CH₃COCH₃). The energy released from forming this new bond is greater than the energy required to break the initial dipole-dipole interactions, resulting in a net release of heat.
3. What specific type of bond forms between acetone and chloroform molecules?
A specific intermolecular force known as a hydrogen bond is formed between acetone and chloroform. The partially positive hydrogen atom on the chloroform molecule is strongly attracted to the lone pair of electrons on the highly electronegative oxygen atom of the acetone molecule. This strong attraction is the primary reason for the observed exothermic reaction and negative deviation from Raoult's Law.
4. How does the interaction between acetone and chloroform demonstrate a deviation from Raoult's Law?
The acetone-chloroform mixture shows a negative deviation from Raoult's Law. Raoult's Law applies to ideal solutions where intermolecular forces are uniform. However, due to the formation of strong hydrogen bonds, the attraction between acetone and chloroform molecules (A-B) is stronger than the attractions in the pure components (A-A and B-B). This makes it harder for molecules to escape into the vapour phase, leading to a lower total vapour pressure than predicted by the law.
5. What are the observable consequences of the negative enthalpy of mixing in an acetone-chloroform solution?
The negative enthalpy of mixing (ΔHmix < 0) results in several measurable effects for the solution. These include:
- Volume Contraction: The stronger attraction pulls molecules closer together, causing the final volume to be less than the sum of the initial volumes (ΔVmix < 0).
- Lower Vapour Pressure: Molecules are held more tightly in the liquid, reducing their tendency to vaporise.
- Increased Boiling Point: More energy is needed to overcome the strong intermolecular forces, which can lead to the formation of a maximum-boiling azeotrope.
