WEEK #1 - LAB #1 – Solution Chemistry

OBJECTIVE: The primary objective of this lab is to practice and fine-tune your solution preparation skills.

INTRODUCTION/THEORY: In this lab, you will witness the chemistry behind dyeing fabric. There are three fabric dyes, red, blue, and yellow, which you will quantitatively measure and dissolve in water with salt and urea. Urea, H2NCONH2, is a water –soluble compound that, due to its hydrophillic properties, keeps the fabric moist during the dying process. Before the fabric is dyed, it is washed with a solution of soda ash (sodium carbonte). Due to the basicity of the soda ash solution, the OH bond on the cellulose (the chemical makeup of the fabric) loses a H+ resulting in an O- . The O- is now a binding site for the dye.1 The dye solutions of the primary colors will then be mixed to form other colors which will all be quantitatively deposited onto your fabric with a micropipette.

EXPERIMENTAL PROCEDURE #1:

You will work as a class in teams of 4 for this lab

The following steps need to be performed. It will be up to the group as to how to distribute the work.

1. Cover your lab bench space area with Saran Wrap and take a bandana and write your name on it in BIG letters in one of the corners with a black Sharpie.

2. Put your marked bandana in a beaker and fill it with enough pre-wash solution of soda ash (already made) so that your bandana is fully covered with solution. LIMIT contact of the soda ash solution with your skin as it is BASIC. There are gloves in the lab that you can wear.

3. Each team of 4 will make a solution of a different dye (red, blue, or yellow)

4. Weigh out the amount of dye needed to make 200 mL of dye solution (1fl.oz. = 29.57mL)

Red – 2.03g in 8oz of water

Blue – 4.29g in 8oz of water

Yellow - 2.47g in 8oz of water

** Show all calculations in your notebook for your pre-lab

5. Weigh out the amount of salt (NaCl) needed so that the concentration of salt (NaCl) in your dye solution is 2.14M.

** Show all calculations in your notebook for your pre-lab

6. Weigh out the amount of urea needed so that the concentration of urea in your dye solution is 0.29M.

** Show all calculations in your notebook for your pre-lab

7. Measure out 200mL of water (decide what you will use to measure out the water) and mix the dye with the salt and urea. Once your dye solution is made, place it at the front of the lab for others to use.

8. Remove your bandana from pre-wash solution, ring dry (the drier; the better) and lay flat (try to remove wrinkles) on your lab bench on top of some Saran Wrap.

9. Each group member should now measure out 5mL of each dye (red, blue, and yellow) with a graduated cylinder and pour into small beakers.

10.With a micropipette, each person should accurately pipet 100µL of each dye into their well-plate according to the matrix below. For example, 100µL of red should be added to 100µL of red. Fill in the colors that you make!

If available, use the pipets that are marked 10-100. The pipets marked 100-1000 or P1000 can be used but are not as accurate.

R / Y / B
R
Y
B

11. From the additional colors made in step 10 and the original colors, each person should now again accurately pipet 100µL of each dye into their well-plate according to the matrix below. For example, 100µL of red should be added to 100µL of orange (that you made in step 10).

If available, use the pipets that are marked 10-100. The pipets marked 100-1000 or P1000 can be used but are not as accurate.

O / P / G
R
Y
B

12. Modeling the 12 color wheel below, add your colors to your bandana in 10µL amounts with a micropipette. Be accurate in the placement of your colors.

If available, use the pipets that are marked P10, P20, or 2-20.

EXPERIMENTAL PROCEDURE #2:

You will work as a class in teams of 4 for this lab

The following steps need to be performed. It will be up to the group as to how to distribute the work.

1. Make a 30 color wheel around your original 12 color wheel modeling the figure below. You should have enough of your original red, yellow, and blue dye to do this.

a.  Use the multiwells to make the mixtures such as the R:Y 90:10.

b.  Add the color mixtures to your bandana in 10µL amounts with a micropipette. Be accurate in the placement of your colors.

If available, use the pipets that are marked P10, P20, or 2-20.

2. When you are finished, let your bandana to dry on your benchtop along, leave the Solution Chemistry Lab Grade Sheet (next page of your notebook) which should have your name on it, and leave your lab notebook copies. Also, make sure your area is clean.

Solution Chemistry Lab

Grade Sheet

Name
Maximum grade that can be earned / 100
Pipet Spot Size / Application (-10 maximum for incorrect volumes and poor application of solution)
Color Matching (-5 maximum for not matching colors in wheel)
Mixing in Wells (-1 for each solution not mixed)
Circle (-1 if not a circle)
Grade