Plant Pigment Chromatography: Comparing Different Plant Materials
Science Lab · Grade 8
Shared by Nimisha · Free to use as a template on AssessmentWiz.
Type
science_lab
Pre Lab
Background: Have you ever wondered why leaves turn red and orange in the fall, or why some flowers are purple while others are yellow? The answer lies in tiny molecules called **pigments** — chemicals inside plant cells that absorb certain wavelengths of light and reflect others. The color we see is the light that bounces back into our eyes. Plants contain several different pigments, and many of these are hidden beneath the dominant green color of **chlorophyll**, the pigment plants use to capture sunlight for photosynthesis.
Scientists use a technique called **chromatography** to separate mixtures of pigments. **Chromatography** works because different pigment molecules have different sizes and different attractions to two things: the **chromatography paper** (called the stationary phase) and the liquid **solvent** (called the mobile phase). When the solvent travels up the paper, it carries the pigments with it — but lighter, less-attracted pigments travel farther up the paper, while heavier, more-attracted pigments stay closer to the bottom. This separates the pigments into distinct colored bands.
Not all plants have the same pigments. Green plants like spinach and kale are rich in chlorophyll, while red cabbage and fall leaves get their colors from pigments called **anthocyanins** — reddish-purple molecules that are also sensitive to pH. By comparing the **chromatography** results from different plant materials, scientists can learn about each plant's unique pigment profile. In this lab, you will act as scientists, using **chromatography paper** and a non-toxic **solvent** to separate and compare the **pigments** found in three to four different plant materials.
Vocabulary
Term: chromatography
Definition: A technique used to separate the components of a mixture based on how they move through a stationary material when carried by a moving liquid or gas.
Term: pigment
Lab Type
Post Lab
Standards
Safety Level
Teacher Notes
Estimated Time
Experiment Design
Research Question
Learning Objectives
Preview shown. The full assessment (all questions, answer key, and teacher notes) loads with the page.