Tuesday, February 18, 2014
Objective:
Use the process of dying fabrics to illustrate chemical reactions, equilibrium, chemical bonding, and pH.
Pre-lab questions:
1.) Where
did the art of dying fibers originate?
The
art of dying fibers has often been referred to as a product of prehistory.
Archaeologists have linked tie-dying to several civilizations. A primal example
being China. It is known that they began the colorful trend during the sixth
century. The Chinese learned how to turn, fold, and tie the material. In doing
so, they were able to differentiate between the parts of the fabric that would
absorb a particular dye. It also caused the designs on different parts of the
material to show color more intensely than others. However, only high-ranking
citizens, such as Priests and wealthy people were allowed to wear the tie-dyed
clothing.
2.) Originally,
what type of substances were used to dye? Originally most substances were found
in nature, i.e. the plant kingdom. Common uses came from parts of plants. Some
examples include the bark, berries, flowers, leaves, and roots.
3.) What
are the fibers of the shirt made of?
The
shirt consist of cotton.Cotton is made
of long strands of cellulose molecules
that are essentially wrapped around each other. Due to the fibers naturally
void nature, the dye molecules are able to form bonds on both sides of the
fiber. If molecules of dye and cotton are together, minor changes will occur.
When the process begins, the atoms on the surfaces of the molecules are
prepared for bonding.
4.) What
chemical interaction is occurring when fibers are dyed?
Ionic bonding occurs during the
tie-dying experiment. After we increased the pH by saturating it in calcium
carbonate, it cause the release of an H atom of the cellulose molecule. Therefore,
the atom now lacks stable octets. Now, the dye is able to bond to the cellulose
molecule.
Lab safety rules:
1.) Always wear safety glasses in the lab.
2.) Wear disposable plastic gloves and aprons.
3.) Don't get sloppy or squirt others with the dye solutions.
4.) Use caution handling the solutions. These are strong chemicals that can be harmful
Procedure:
Step 1: With a permanent marker, write your name on the cloth you will be tie dying. There will be many other shirts in the lab during this activity; be sure yours is marked to avoid losing it.
Step 2: Soak your cloth in the hot water for about 5 minutes. Be sure you put it in the tub marked for your period.
Step 3: Put on a pair of gloves, remove your cloth from the soaking tub and wring out. Using the below diagrams, tie you cloth in one (or a combination of) the methods shown using string or rubber bands.
Step 4: Dye application. Apply the dye using the applicator bottles. Be aware that mixing will occur where the dyes come in contact with each other. Using complimentary colors (purple and yellows, blues and orange, or red and green) near each other usually produces a brownish black color. Also, the more dye you put on a given spot, the less white will remain on the final product.
Step 5: Place your dye-soaked item in a grocery or other plastic bag marked clearly with your name. No pooling of liquid should appear in the bag.
Step 6: After the cloth has soaked for at least 24 hours, open the bag, remove the item, and rinse it several times with warm water, before removing strings or rubber bands. Once it is rinsing clean, remove the ties and rinse several times again until it is rinsing clean. At this point, you can hang it to dry or place it in another bag to take home and wash.
3:05 PM