Paper Chromatography Lab

(Separating Mixtures)

 

 

Pre-Lab:

Lab Objective: Create a process for separating a mixture, specifically an ink mixture.

1.) What colors are mixtures?
     Green(blue + yellow), purple(red + blue), orange(yellow + red), grey,
     Black?-dark colors like blue, purple, brown, etc.

2.) What substances could be used to separate a mixture?

     Water, alcohol, bleach, acetone, vinegar, ammonia, hydrogen paroxide, etc.

3.)What is Paper Chromatography?

   * Chromatography is a method for analyzing complex mixtures (such as ink) by separating them into the chemicals from which they are made.

       - www.yesmag.bc.ca/projects/paper_chroma.html     

 

What is the set up for Paper Chromatography?

 

 Alcohol and Water:

 

 

Hypothesis Questions:

1.) Are colors mixed to make other colors?
   - Depending on the color you are trying to make, depends if it is necessary to mix colors to make it.

2.) Can mixed colors separate into their components colors?
   - Yes, but in order to do so you have to use specific substances.

3.) Can black separate into its component colors? Which colors will separate out?

   - I do believe black can be separated into its component colors.

   - The colors that may separate are dark colors like blue, red, brown, etc.

Materials

• Goggles
• Black Markers
• Strips of Filter Papers
• Metric Ruler
• Plastic Cup
• Rubbing Alcohol
• Tape
• Pencil

Procedure:

 1.Using the ruler, cut the filter paper into long, rectangular strips, about 3 cm x 10cm. *You need 2*

 2.Measure 0.5 cm from the bottom of the paper strip and draw a horizontal line with your pencil across the width of the strip. Then, use the black marker to make a dot on the pencil line.

 3.Tape the paper strip around the pencil so that the very bottom of the strip touches the alcohol.
        **Do not let ink dot touch alcohol

 

 4. Pour rubbing alcohol into a plastic cup to a depth of ½ cm. Then, rest the pencil on the rim of the cup so that the end of the pencil strip with the ink mark is just barely in contact with the alcohol.

 5. Observe for about 8 minutes.

 6. Let the strip dry by taping it to a piece of paper provided.  Put group names, period, and ipod # on the sheet.

 7. Repeat the process for the other solution for the same marker.

Data Table:

  

Observations	Observation at 3 minutes	Observation at 6 minutes	Dry test strips
(Sharpie) black marker w/ alcohol	the alcohol has not reached the black dot	the alcohol has reached the top of the dot but nothing has happened	nothing changed because the alcohol never got the chance to surpass the dot
Black marker w/ H2O	the water is half way up the dot	the water has passed the top of the dot but nothing has changed	the water surpassed the dot but nothing changed

Data:

 Alcohol:

 

Water:

 

 

 

 

 

Analysis and Conclusions:

 

 1.) What appeared on the filter paper?  Describe all results.

  - Nothing appeared on the filter paper because the alcohol did not have enough time to surpass the dot.

 2.) What did the results indicate about the black ink? *What classification of matter could you give the ink?

  - The results indicate that the black ink is made up of different color mixtures.

 3.) Is chromatography a useful separation method for ink mixtures? Explain based on your results. 

  - Based on my groups results no because we had to let it sit longer in the solvent, but on other groups yes.

 

 4.) If you could alter the experiment to test another condition or factor, what would you change or test?

  - I would test it with the alcohol for a longer time or change the substance to see what results I would get.

  

Post Lab:

 

How does paper chromatography work?  What do the results tell us? A: Preferential adsorption of chemical compounds (gases or liquids) in an ascending molecular-weight sequence.