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The purpose of this experiment is to detect the various contents of a mixture and separate various substances using chromatography.
This experiment investigates the effect of different solvents on substances in a mixture using chromatography. Chromatography is based on the principle that it allows the separation of molecules in a mixture by moving them from a stationary phase to a mobile phase (Coskun, 2016). The stationary phase remains fixed, either as a liquid or solid, while the mobile phase carries the solvent (Asante, 2016).
The ability to isolate complex mixtures is crucial in various fields, such as the pharmaceutical industry, to ensure the safety of products for patients (Kisley and Landes, 2014).
The following steps were followed to conduct the chromatography experiment:
These results were recorded.
Solution | Solvent Front | Spot Distance | Rf (Retention Factor) |
---|---|---|---|
Ethanol | 1.70 cm | 1.40 cm | 0.82 cm |
Isopropanol | 1.00 cm | 0.50 cm | 0.50 cm |
Propanone | 2.80 cm | 2.50 cm | 0.89 cm |
Mixture of Above | 1.00 cm | 0.20 cm | 0.20 cm |
* All results are to 2 decimal places.
The calculated Rf values for each solution are obtained using the formula: Rf = Spot Distance / Solvent Front
The results clearly demonstrate a relationship between the polarity of compounds and their Rf values. Higher Rf values indicate less polar compounds, while lower Rf values suggest non-polar compounds (Bele and Khale, 2011). Polar substances tend to dissolve more in polar solvents, while non-polar substances dissolve more in non-polar solvents (Ng and Kushairi, 2017).
In this experiment, the pigments in plant leaves, such as chlorophyll and carotenoids, are non-polar. When dipped in non-polar solvents like propanone, they exhibit the highest Rf values, indicating a stronger affinity for the non-polar solvent and spending more time in the mobile phase. Conversely, when dipped in ethanol, which is more polar, the pigments exhibit lower Rf values, suggesting less interaction with the solvent and more time in the stationary phase.
However, it's worth noting that isopropanol should have theoretically shown a higher Rf value than ethanol due to its higher polarity (osu.edu, 2022). The discrepancy in the results could be attributed to experimental errors, such as incomplete adsorption, which might explain the lower values. To minimize errors, it is essential to allow the paper to fully dissolve in the solvent to obtain more accurate readings.
Comparing the experimental Rf values with published data (Table 2), the pigments in the experiment can be identified. For example, an Rf value of approximately 0.45 corresponds to chlorophyll a when dipped in isopropanol. Additionally, an Rf value of 0.82, obtained when dipped in ethanol, corresponds to phaeophytin, while dipping in propanone (Rf = 0.89) suggests the presence of carotene (Rf = 0.95).
Pigment | Rf Value |
---|---|
Carotene | 0.95 |
Phaeophytin | 0.83 |
Xanthophyll | 0.71 |
Chlorophyll a | 0.65 |
Chlorophyll b | 0.45 |
Table 2: Rf values of pigments (pearsons.com, 2016)
Solution | Hazard | Risk | First Aid Measures | Protective Measures |
---|---|---|---|---|
Ethanol | Volatile, Flammable | Serious eye irritation | Rinse eyes cautiously with water for several minutes. Rinse skin with water and remove all contaminated clothing. Seek medical attention if eye irritation persists. | Wear protective gloves, clothing, eye protection, and face protection. No smoking. Keep away from heat, hot surfaces, and other ignition sources. |
Isopropanol | Flammable, Irritant, Serious eye damage, Dizziness, and drowsiness | Rinse eyes cautiously with water for several minutes. Rinse skin with water and remove all contaminated clothing. Store locked up. | Wear protective gloves, clothing, eye protection, and face protection. No smoking. Keep away from heat, hot surfaces. | |
Propanol | Flammable, Irritant, Specific target organ toxicity, Serious eye damage, Dizziness, and drowsiness | Rinse cautiously with water for several minutes. Call poison center/doctor. | Wear protective gloves, clothing, eye protection, and face protection. No smoking. Keep away from heat, hot surfaces, and other ignition sources. |
Chromatography Experiment Lab Report. (2024, Jan 04). Retrieved from https://studymoose.com/document/chromatography-experiment-lab-report
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