Chromatography

A widely used separation tool

Purpose: Given a sample of unknown ink, we were to use chromatography paper to determine the identity of the sample. And also, we were to separate two dyes of different color using a silica gel column, made in lab.

Procedure: Lab manual Experimental Chemistry pg.47-50. There were no changes made to this lab.

Experimental measurements and Data: See attached page of results from the chromatography experiment. There was no data or measurements for the separation of the dyes using the silica gel column.

Calculations and Data analysis: There were no equations used in this lab, it was a primarily visual lab. With the chromatography paper experiment, we were given unknown A . After placing both unknown A and a piece with the five pens on it in each of the unknowns (water, non-acidic ethyl acetate, HCl and NaOH) we had nice examples of capillary action. We looked at the unknown and whether it separated in comparison to all five ink samples.

Ink 1 Ink 2 Ink 3 Ink4 Ink 5 Unknown A

Water

non-acidic ethyl acetate

HCl (acid)

NaOH (base)

From this chart, we could see that unknown A had common traits with ink 3 through out each test, plus by looking at the actual data (attached page) the colors separated out and the height of the bleeding column match almost identically. I would say that unknown A in ink 3.

With the separation of the different color dyes in a silica gel column, we had a few problems establishing an initial gel column. But after many failed attempts, we finally got moving. There was nothing more to this part of the experiment than to watch what would make each dye separate and how they would separately flow down through the silica gel. We then checked the final color to determine the acidity or basic quality of each dye.

Conclusion: Using the chromatography paper we discovered that unknown A was our ink 3. Judging by, separation, colors separated and height of the bleeding column, there were no close calls. There might have been room for improvement in this experiment in that we put the ink dots below the pencil line, not on the pencil line, so that we had to pt a VERY small amount of each liquid in each beaker, making sure not to directly touch each dot.

In the silica gel separation, there was room for improvement in just establishing a silica gel column. It was difficult to determine how much glass wool we needed, with nothing to go by.