CHALK CHROMATOGRAPHY WORKING MODEL

CHALK CHROMATOGRAPHY

Chalk chromatography is a simple and educational experiment that demonstrates the principles of chromatography using chalk as the stationary phase and water as the mobile phase. It’s commonly used in classrooms and science fairs to introduce students to the concept of chromatography and the separation of mixtures. Here’s how you can perform chalk chromatography:

**Materials:**
1. Chalk (white or colored)
2. Water
3. Small cups or containers
4. Coffee filters or blotting paper
5. Scissors
6. Pencil or marker
7. Tape or paper clips
8. Optional: Various markers or colored pens for comparison

**Procedure:**
1. **Preparation of Chalk Strips:**
– Cut the chalk into small pieces or strips using scissors.
– Prepare a few chalk strips of different colors if using colored chalk.

2. **Preparation of Mobile Phase:**
– Pour water into small cups or containers. The water will act as the mobile phase.

3. **Setting Up the Chromatography:**
– Take a piece of coffee filter paper or blotting paper and draw a horizontal line across the paper using a pencil or marker. This line will serve as the origin for the chromatography.
– Tape or clip the chalk strip near the bottom of the paper, just above the origin line. Ensure that the strip does not touch the water.

4. **Chromatography Process:**
– Place the bottom edge of the paper strip into the water in the cup, ensuring that the chalk strip remains above the water level.
– Allow the chromatography to proceed by capillary action. The water will move up the paper, carrying the chalk components with it.
– Observe the separation of colors as the water travels up the paper. Different colors in the chalk may separate into distinct bands.

5. **Observation and Analysis:**
– After the water has traveled up the paper sufficiently (usually after 10-20 minutes), remove the paper from the cup.
– Allow the paper to dry completely, then observe the chromatogram. You should see colored bands corresponding to the different pigments present in the chalk.

**Discussion:**
– Chalk contains various pigments that give it its color. These pigments can be separated based on their solubility in water.
– The chromatography process separates the pigments by their affinity for the mobile phase (water) and the stationary phase (chalk and paper).
– The separation occurs because each pigment has a different solubility in water and interacts differently with the paper. Pigments that are more soluble in water will travel further up the paper, while less soluble pigments will remain closer to the origin.

Chalk chromatography provides a hands-on demonstration of chromatographic principles and can be used to discuss concepts such as solubility, polarity, and the behavior of pigments in mixtures. It’s a fun and interactive way to engage students in science and chemistry education.

Safety Precautions:

• Conduct the experiment in a well-ventilated area.
• Handle solvents with care and follow safety guidelines.
• Avoid direct contact with the eyes, skin, or mouth while handling chemicals.

Chalk chromatography is not only an educational experiment but also a visually captivating way to explore the science of color separation and chromatographic techniques.