 Introduction: Everything we do, from digesting our food to making art, involves chemistry. Everything is made of chemicals! Today, we are going to learn about how chemistry is involved in tie dying. First we need to understand a few things about dyes and how they react.

 Some dyes, such as the kind that you can buy in the grocery store, really just stain clothes, so the dye washes out a little every time you wash the cloth. Is this a chemical or physical change?____________ PHYSICAL

 A really good dye actually attaches to the molecules of the fabric (this is known as ___________________________.)  The dye will not wash out. Is this a chemical or a physical change?______________ COVALENT BONDING CHEMICAL

The dye molecules are made out of atoms of different elements such as  C, H, O, N, S, Na, Cl These dye molecules are called chromophores

RED BLUE

 Different dye colors are made out of different dye molecules. Each dye molecule is shaped differently and thus each different shape absorbs light differently.

c = C = speed of light, a constant (2.998 x 10 8 m/s) = frequency, in units of hertz (hz, sec -1 ) = wavelength, in meters Electromagnetic radiation propagates through space as a wave moving at the speed of light.

Long Wavelength = Low Frequency = Low ENERGY Short Wavelength = High Frequency = High ENERGY Wavelength Table

E = h E = Energy, in units of Joules h = Planck’s constant (6.626 x J·s) = frequency, in units of hertz (hz, sec -1 ) = frequency, in units of hertz (hz, sec -1 ) The energy (E ) of electromagnetic radiation is directly proportional to the frequency ( ) of the radiation.

Relating Frequency, Wavelength and Energy Common re-arrangements:

PLANCK’S PRACTICE PROBLEMS A photon of light reflected by a dye molecule has an energy of x kJ. Calculate the frequency and the wavelength of the photon. Frequency = 4.57x10 14 hz, 456 terahertz Wavelength = 6.56x10 -7 m, 656 nm

 The fabric your clothing is made out of is also made of molecules. Cotton, which grows on a cotton plant, is made of large strands of cellulose molecules, all twisted together. Cellulose is the same thing that wood is made of! See picture below:

How do Reactive Dyes Work? Fiber Reactive Dyes are so called because they under go a chemical reaction with the fiber during which they form a covalent bond to the fiber. The dyes have a reactive molecular group on them that reacts with the hydroxyl (-OH) groups on of cellulose fibers, so they can be used on cotton, hemp, linen, rayon and other plant based fibers.

 Sodium carbonate  Na 2 CO 3  What is reaction in water???  CO H 2 O → HCO OH -

 What will be the pH of a 10.0L solution in which 75.0g of sodium carbonate is dissolved? For carbonic acid (H 2 CO 3 ) the K a1 = 4.30 x and the K a2 = 5.62 x ?  CO H 2 O → HCO OH -  HCO H 2 O → H 2 CO 3 + OH - pH=11.550

1.it can make it possible to dissolve more dye in a given volume, for the strongest of colors 2.it serves as a humectant, or water-attractor, to help keep fabric damp long enough for the reaction to occur. Where does urea come from? Urea is the same chemical as is found in the urine of mammals, but the urea we buy is not obtained from urine. It is synthesized from natural gas. Is urea hazardous? No, urea is reasonably safe, compared to many other chemicals. It's a major ingredient in many skin moisturizers, due to its humectant properties. Although you should avoid skin exposure to dyes or soda ash, skin exposure to urea is not a major safety issue. It may be irritating to the skin. Airborne urea, like most powders, is hazardous when inhaled. Urea has two purposes:

 Label your item with a permanent marker  Place it into the bucket of a solution of soda ash that has been prepared.  Completely submerge it and be sure that it is soaked through. We will let it soak overnight.

 You must wear an apron and plastic gloves.  The tee shirt should be wet but most of the water squeezed out. If too wet, the dye will be diluted.

 Lay the shirt flat on the clean plastic tabletop.  Try to get as many wrinkles out of the shirt.  Pick a pattern. Pleat, spiral, or fold the shirt in the desired pattern.

 Make sure the area is clean.  Place the shirt on the table and begin applying the dyes to the areas desired using the dropper that is in the dye.  Be careful when choosing colors. Orange + blue will turn brown.  Suggestions: Don’t put purple next to yellow or orange. This will also turn brown.

 One thing to pay attention to is the amount of dye added.  You want to get enough dye into the shirt so that white spots disappear, but too much dye will cause it to run and mix.  Try to balance this.  Spread the pleats apart and look. If you see white, add more dye.

 Wrap shirt in saran wrap to prevent drying out.

 Wearing gloves and goggles, take the bag to the sink.  Remove the shirt.  Rinse the shirt with cold water. Squeeze and rinse until no more dye runs from the shirt (This may take 5-10 minutes).  Increase the temperature of the water to warm water. Continue to rinse for 5 more minutes.  Squeeze shirt dry. Place shirt in new plastic bag.  Suggestion—use 2 plastic bags to avoid leaking.

What is Synthrapol?  Synthrapol is a special detergent used in pre-scouring fibers before dyeing, and in washing out fiber reactive dyes after dyeing. It is exceptionally good at removing Procion dyes from fabric.  A detergent contains long, thin molecules which each have one end that "likes" oily substances, and another end that "likes" water. Detergent molecules will completely surround a tiny particle of something too oily to be washed away by water alone, leaving just their water-loving 'tails' sticking out, to be easily swept away by the water. Water is the strongest of all solvents, but it requires detergents to wash away oily substances. Ingredients  The actual contents of Synthrapol are water, isopropanol (which is ordinary rubbing alcohol, a chemical "known to the state of California to cause reproductive harm", thus the alarming warnings on the label), and the detergent itself, a combination of ethoxylated and sulfated aliphatic alcohols.