5 Steps to a 5 AP Chemistry 2019

Experimental Investigations ❮ 291

is drawn up the strip by capillary action, it dissolves the sample. The various solutes have

different affinities to the paper and to the solvent and can thus be separated as the solvent

moves up the strip. Choice of the solvent is critical and can be related to its polarity; how-

ever, the choice sometimes must be done by trial and error.

Equipment

Filter paper or chromatography paper

Chromatography jar

Various solvents

Metric rules

Sample to be analyzed

Assorted glassware

Measurements

The student will make measurements of the distance that each component travels and the

distance that the solvent traveled.

Calculations

The calculations involve determining the Rf value for each component. The Rf value is the

distance the component travels divided by the distance the solvent traveled. Substances

that interact strongly with the paper do not travel very far (low Rf values), while those that

interact strongly with the solvent travel much farther (high Rf values).

Comments

Chromatography is a very powerful separation technique.

Experiment 6: Determination of the Type of Bonding

in Solid Samples

Synopsis

In this type of experiment, the student is given a set of bottles that contain solids of vari-

ous types of bonding—ionic, covalent, or metallic. The student uses various physical and

Capillary tube

(a) Spotting the Chromatography Paper

Solvent

(b) Chromatography Development Jar

Figure 19.3 Basic procedure for a paper chromatography experiment.