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Gas chromatography (GC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are techniques used in analytical chemistry - Leaving Cert Chemistry - Question c - 2013
Question c
Gas chromatography (GC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are techniques used in analytical chemistry. (i) State th... show full transcript
Worked Solution & Example Answer:Gas chromatography (GC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are techniques used in analytical chemistry - Leaving Cert Chemistry - Question c - 2013
Step 1
State the principle on which all chromatographic techniques are based.
Answer
Chromatographic techniques are based on the principle of separation of components in a mixture. This is achieved by utilizing a mobile phase, which is often a solvent, that moves through a stationary phase. The components of the mixture have different affinities for the stationary phase, causing them to separate as they pass through.
Step 2
Step 3
Describe an experiment you carried out in the school laboratory to separate a mixture of indicators using thin-layer, paper or column chromatography.
Answer
In this experiment, I used paper chromatography to separate a mixture of indicators.
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Preparation: I applied the mixture using a dropper onto a piece of chromatography paper, making a spot approximately 2 cm above the bottom of the paper.
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Eluent: I then prepared a solvent (the eluent) that I would use for the separation process and poured it into a suitable container, ensuring that the solvent level was below the spot where the mixture was applied.
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Developing the Chromatogram: I placed the paper in the container, allowing it to sit upright without allowing the spot to touch the solvent. The paper absorbed the solvent, and the mixture began to separate as it moved up the paper.
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Observation: As the solvent traveled, I observed the different indicators separate into distinct spots based on their respective affinities for the paper and the solvent.
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Analysis: After allowing the solvent to travel to a predetermined distance, I removed the paper and let it dry, which enabled me to analyze the separated components of the mixture, observing how far each indicator traveled.