Chem 001: Problem Solving Investigation in Analytical Chemistry

PROBLEM

Are red flowers really red?

Two students were having an argument about pigments in red flower. One said that red petals can only contain the red color, whereas the other students thought that the red color could actually be a mixture of color. Plan an experiment to investigate if the pigment in red flowers consists of one or more colors. In your investigation think about how you can extract the pigment and check whether it consists of one or more color.

PLAN FOR INVESTIGATION

A. Purpose of the Investigation

The purpose of this investigation is to know whether the pigment in red flowers consist one or more colors. The goal of this experiment is to analyze the pigments found in flowers using paper chromatography.

B. Materials/ Apparatus

The materials used in this experiment include filter paper, scissors, pencil, ruler, clean jar or drinking glass, large- mouth glass jar, water (at least 60 mL, distilled water is preferable, but tap water is also suitable), 70% isopropyl alcohol, measuring cup, piece of scratch paper, coin, timer or clock, and of course red flower petals. You will need at least 2 flower petals from at least 3 different plants. Tip: Larger petals work better than smaller petals.

C. Steps/ Procedure

Cut the chromatography filter paper into strips that are about 2 cm wide and as long as the large-mouth glass is tall (the strips should all be the same size). You will want to make at least three strips for each flower you want to investigate, or a minimum total of nine strips.

Use a ruler and pencil to draw a line across each paper strip, horizontally, 2 cm from the bottom, as shown in Figure 1. This is the origin line, where the sample will later be spotted. Tip: Do not use a pen for writing on the strips because the ink will run when the solvent