Experiment 2D

PROCEDURE
Part I Setting Up

Experiment 2D: Separation of a mixture by Paper Chromatography

Objectives:
1. To assemble and operate a paper chromatography apparatus
2. To study and the significance of Rf values
3. To test various food colorings and to calculate their Rf values
4. To compare measured Rf values with standard Rf values
5. To separate mixtures of food coloring into their components
6. To identify the components of mixtures by means of their Rf values

Materials / Apparatus: See “Health Chemistry Lab Experiments” page 24-29
** Substitute capillary tubes for stirring rods**

Procedure: See “Health Chemistry Lab Experiments” page 24-29

DATA AND OBSERVATIONS
Part II Rf Values of Individual Food Colorings

Table 1: Results for Lab Station
Colour tested
Blue
Distance solute travelled d1
6.65 +/- 0.01
Distance solvent travelled d2
6.65 +/- 0.01
Ratio from fronts Rf
1.00

Table 2: Class Results
Lab Station
Colours Tested

Red Rf
Yellow Rf
Blue Rf
1) Luti, Ashley, Carina
0.82

2) Thomas H, Maaz, Aiden, Jesse

1.00
3) Ivy, Erica, Victoria, Megan

0.93

4) Marko, Trent, Gerry

0.85

5) Sean, Katie, Licheng, Madison
0.74

6) Lauren, Stephanie

1.00
Average Rf Values
0.78
0.89
1.00

Part III Separations of Mixtures into Their Components

Table 3

Component Colours
D1 (cm)
D2(cm)
Calculated Rf
Component Rf (from table 2)
Green Colouring
Yellow, Blue
B: 8.15
Y: 6.55
8.15
B: 1.0
Y: 0.80
B: 1.0
Y: 0.89
Unknown Mixture
Red, Yellow, Blue
R: 5.72
Y: 6.18
B: 7.10
7.10
R: 0.81
Y: 0.87
B: 1.0
R: 0.78
Y: 0.89
B: 1.0

Table 4
Dye
Red #2
Red#3
Red#4
Yellow#5
Yellow#8
Blue #1
Blue #2
Rf
0.81
0.41
0.62
0.95
0.77
1.0
0.79

Observations
The solvent (water) always travelled farther than the solute, except in the case of blue, which travelled the same amount as the solute. The blue had an Rf value of 1.0. The green and the unknown mixture both separated into their component colours and each component colour travelled a different distance.

Questions
1. a) The blue we