Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What laboratory technique is used to observe the different pigments in a material?

1. Filtration

2. Paper chromatography

3. Fractional distillation

4. Spectroscopy

The correct answer is: Paper chromatography

The technique used to observe the different pigments in a material is paper chromatography. This method is particularly effective for separating and identifying compounds based on their movement through a stationary phase, such as paper, when a solvent passes through the material. In paper chromatography, a small spot of the mixture to be analyzed is placed on the paper. As the solvent moves up the paper, it carries the different components of the mixture at different rates, allowing for the separation of pigments. Each pigment will produce a distinct band on the paper, and this can be visually observed or quantified to analyze the composition of the sample. In contrast to paper chromatography, filtration is a technique used to separate solids from liquids or gases using a medium that only allows certain substances to pass through. Fractional distillation separates components of a mixture based on differing boiling points, which is not suitable for isolating pigments. Spectroscopy analyzes the interaction of light with matter but does not directly separate components for observation like chromatography does.