Chloroform, a dense, colorless, and volatile liquid, is a widely used solvent in various industrial and laboratory applications. Its unique solubility properties make it an essential compound in numerous chemical processes. This comprehensive guide delves into the intricate details of chloroform’s solubility, providing a wealth of information for science students and professionals.
Understanding Chloroform’s Solubility in Water
Chloroform’s solubility in water is remarkably low, with a solubility of only 8 g/L at 20°C. This can be attributed to the polar nature of water molecules and the non-polar character of chloroform. Water molecules are strongly attracted to each other through hydrogen bonding, creating a structured network that makes it challenging for non-polar chloroform molecules to dissolve effectively.
The solubility of chloroform in water can be expressed using the following equation:
S = Ksp / (1 + Ksp)
Where:
– S is the solubility of chloroform in water (in mol/L)
– Ksp is the solubility product constant for chloroform in water, which is approximately 5.3 × 10^-3 at 25°C.
By substituting the value of Ksp into the equation, we can calculate the solubility of chloroform in water at 25°C:
S = (5.3 × 10^-3) / (1 + 5.3 × 10^-3)
S = 5.29 × 10^-3 mol/L
This corresponds to a solubility of approximately 8 g/L at 20°C, as mentioned earlier.
Chloroform’s Solubility in Organic Solvents
In contrast to its low solubility in water, chloroform is miscible with a wide range of organic solvents, such as alcohols, ethers, and hydrocarbons. This is due to the non-polar nature of chloroform, which allows it to readily dissolve in other non-polar or weakly polar solvents.
The solubility of chloroform in various organic solvents can be quantified using the Hildebrand solubility parameter, which is a measure of the cohesive energy density of a substance. The Hildebrand solubility parameter for chloroform is approximately 9.3 (MPa)^0.5, indicating its affinity for solvents with similar solubility parameters.
To illustrate the solubility of chloroform in organic solvents, consider the following examples:
| Solvent | Solubility of Chloroform |
|---|---|
| Ethanol | Miscible |
| Acetone | Miscible |
| Benzene | Miscible |
| Hexane | Miscible |
The high solubility of chloroform in these organic solvents is a result of the favorable intermolecular interactions between the non-polar chloroform molecules and the non-polar or weakly polar solvent molecules.
Partition Coefficient of Chloroform
The partition coefficient, also known as the distribution coefficient, is a measure of the relative solubility of a substance in two immiscible solvents. In the case of chloroform, the partition coefficient between chloroform and water is a crucial parameter that reflects its non-polar nature.
The partition coefficient of a substance, such as cholesterol, between chloroform and water can be calculated using the following equation:
P = [solute]_chloroform / [solute]_water
Where:
– P is the partition coefficient
– [solute]_chloroform is the concentration of the solute in the chloroform phase
– [solute]_water is the concentration of the solute in the water phase
For example, the solubility of cholesterol in water is 0.520 mg/100 mL, while its solubility in chloroform is 1.00 g/4.5 mL. Using these values, we can calculate the partition coefficient of cholesterol between chloroform and water:
P = (1.00 g/4.5 mL) / (0.520 mg/100 mL)
P = 1923
This high partition coefficient of approximately 1923 indicates that cholesterol is significantly more soluble in chloroform than in water, further confirming the non-polar nature of chloroform.
Density and Miscibility of Chloroform
Chloroform is a dense liquid with a density of 1.49 g/cm³ at 20°C, which is higher than the density of water (1.00 g/cm³). This higher density causes chloroform to sink in water, making it useful in applications where a denser solvent is required.
In terms of miscibility, chloroform is miscible with a wide range of organic solvents, as mentioned earlier. However, it is only slightly soluble in water, with a solubility of 8.0 g/L at 20°C. This limited solubility in water is a result of the non-polar nature of chloroform and the strong intermolecular interactions within the water network.
Applications of Chloroform’s Solubility Properties
The unique solubility properties of chloroform make it a valuable solvent in various industrial and laboratory applications:
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Extraction and Purification: Chloroform’s high partition coefficient with water allows it to be used effectively in the extraction and purification of non-polar compounds from aqueous solutions.
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Polymer and Plastic Production: Chloroform’s ability to dissolve non-polar polymers, such as polytetrafluoroethylene (PTFE), makes it useful in the production and processing of these materials.
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Refrigerant and Propellant: The high density and low solubility of chloroform in water contribute to its use as a refrigerant and propellant in various applications.
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Analytical Chemistry: Chloroform’s solubility properties make it a suitable solvent for various analytical techniques, such as liquid-liquid extraction and thin-layer chromatography.
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Pharmaceutical and Medicinal Applications: Chloroform’s solubility characteristics have been exploited in the development of certain pharmaceutical formulations and drug delivery systems.
In conclusion, the solubility of chloroform is a complex and fascinating topic that encompasses various aspects, including its low solubility in water, high solubility in organic solvents, partition coefficient, density, and miscibility. Understanding these intricate details is crucial for scientists and engineers working in diverse fields, from chemical processing to pharmaceutical development. This comprehensive guide provides a valuable resource for exploring the nuances of chloroform’s solubility and its practical applications.
References:
- Water–Chloroform Partition Coefficients from Grid Inhomogeneous Solvation Theory: Reliable Information for Drug Development
- Measurement and correlation of solubility of ε-CL-20 in solvent mixtures of chloroform + ethyl acetate and m-xylene + ethyl acetate at temperatures from 278.15 to 313.15 K
- Chloroform – Wikipedia
- The solubility of cholesterol in water and chloroform is 0.520 mg/100 mL and 1.00 g/4.5 mL, respectively. Estimate the partition coefficient of cholesterol between chloroform and water. What conclusion can be drawn about the polarity of cholesterol?
- Chloroform | CHCl3 | CID 6212 – PubChem
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