Study Notes
Chromatography is a method used to separate mixtures and identify different substances based on their distribution between different phases.
- Paper Chromatography — a technique to separate mixtures of soluble substances using a suitable solvent. Example: Separating different colored inks on a paper strip.
- Rf Value — a ratio used to identify compounds by comparing the distance traveled by the substance to the distance traveled by the solvent. Example: Calculating the Rf value to identify an unknown dye.
- Locating Agent — a substance that reacts with colorless samples to produce a visible colored product. Example: Using a locating agent to visualize proteins on a chromatogram.
Exam Tips
Key Definitions to Remember
- Paper Chromatography: A method to separate mixtures of soluble substances.
- Rf Value: The ratio of the distance traveled by a substance to the distance traveled by the solvent.
- Locating Agent: A substance used to make invisible samples visible on a chromatogram.
Common Confusions
- Confusing the solvent front with the ink spots.
- Using pen instead of pencil for the baseline, which can interfere with results.
Typical Exam Questions
- What is paper chromatography used for? To separate mixtures and identify substances.
- How do you calculate the Rf value? Divide the distance traveled by the substance by the distance traveled by the solvent.
- What indicates a pure substance on a chromatogram? A single spot.
What Examiners Usually Test
- Understanding of how to set up and carry out paper chromatography.
- Ability to interpret chromatograms and calculate Rf values.
- Knowledge of how locating agents work and their purpose.