Lab 1. Synthesis of Pigments Spring2024
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Lab 1. Synthesis of Pigments
Procedure to prepare Burnt Ochre (ferric oxide or Iron (III) Oxide (Fe2O3) from natural yellow ochre (hydrated ferric or Iron (III) oxide (Fe2O3·nH2O))
1) Obtain a heat-resistant test tube
2) Add about a spatula full of yellow ochre to the test tube
3) Heat the mixture under the hood using a gas burner for about 5 minutes.
4) Record your observations.
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Observations: Yellow when they mixed. After heating it up it was brown 1 minute after removing it from the fire it started to get red 5 minutes after removing it, it was completely red |
Answer the following
1) Give the chemical formula for yellow ochre Fe2O3·H2O
2) Give the chemical formula for burnt ochre Fe2O3·nH2O-----Fe2O3+nH2O
3) Give the chemical equation for the formation of burnt ochre from yellow ochre
Fe2O3·nH2O=Fe2O3+nH2O
4) If you were weighing the test tube and yellow ochre, would you expect to observe the same weight before and after heating your pigment? Yes/No explain your answer
No, it would not be the same weight because the process of heating it up gets rid of the water in it, so the weight would become less
5) Why is the common term “burnt ochre” used to prepare this red pigment not correct?
6) Where can this transformation be seen/ has been seen in real life?
7) Give a brief history of the use of the pigments (yellow and burnt/red ochre) through time
8) What element is responsible for the colors of yellow and red (or burnt ochre)
Synthesis of Cobalt Blue (or Thenard Blue)
1. Weigh 1 g Cobalt (II)-chloride (CoCl2 · 6H2O) and 5 g Aluminum oxide (Al2O3)
2. Homogenize in a mortar until the mixture is pink.
3. Transfer the mixture to a heat-resistant test tube.
4. Heat mixture with a gas burner for about 5 minutes.
5. Write down your observations.
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Observations Describe what you see from the beginning of the experiment until the end. How easy is to homogenize the mixture, what are the original colors? What is the color of the mixture? What color do you expect to form when you heat up? etc Purple pink when they mixed together. The first 20 seconds it becomes light purple. It becomes blue during the 24-25 seconds, and darker around 45 secons. After about 1 min and leave the mixtue form the fire, the mixture looks boiling |
Answer the following
1) Give the chemical name of Cobalt Blue CoO
2) Give the chemical formula of Cobalt Blue CoO · Al2O3
3) Is Cobalt Blue a stable pigment? Explain your answer
4) Give two examples of the use of Cobalt Blue in an artwork
5) What element is responsible for the color in Cobalt Blue?
6) Give a brief history (paragraph long at least) of the use of Cobalt Blue through time
Synthesis of Cobalt Green
6. Weigh 1 g Cobalt(II)-chloride (CoCl2 · 6H2O) and 5 g Zinc oxide (ZnO)
7. Homogenize in a mortar until the mixture is pink.
8. Transfer the mixture to a heat-resistant test tube.
9. Heat the mixture with a gas burner for about 5 minutes.
10. Write down your observations.
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Observations Describe what you see from the beginning of the experiment until the end. How easy is to homogenize the mixture, what are the original colors? What is the color of the mixture? What color do you expect to form when you heat up? etc when we first mixed it it looked like a very light pink once it started being heated up there was some vaporization that was visible 3 minutes in, it started to be a lot more green by the end of five minutes it was mostly green but the top parts were a bit more blue |
Answer the following
7) Give the chemical name of Cobalt Green CoO·ZnO/ COZnO2
8) Give the chemical formula of Cobalt Green
9) Is Cobalt Green a stable pigment?
10) Give two examples of the use of Cobalt Green in an artwork
11) What element is responsible for the color in Cobalt Green?
12) Give a brief history (paragraph long at least) of the use of Cobalt Green through time
Synthesis of Egyptian Blue
1) Weigh 2.4g of Silica (SiO2), 5.6g of Calcium Oxide (CaO), 1.2g of Copper Carbonate(CuCO3), and 0.1g of Sodium Bicarbonate (NaHCO3)
2) Create a mixture and homogenize it in a mortar and pestle.
3) Once homogenized, place the mixture into a small container
4) Add 3-5 drops of distilled water from a pipette into the mixture.
5) Shape the mixture into a ball about 2 cm wide using your hand (wear gloves!).
6) Let the ball air dry for 1 full day or 24 hrs.
7) Place the ball into a crucible and heat it up to a varying range between 900 and 1000 degrees Celsius at increments of 150 or 200 degrees
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Observations |
Study Questions
1) Give the chemical formula for Egyptian Blue
2) Give the chemical name for Egyptian Blue
3) What element is responsible for the color of Egyptian Blue?
4) Is Egyptian Blue a stable pigment? Explain your answer
Synthesis of Verdigris (at home)- Please start this experiment the same day or day after this lab
1. Obtain a piece of copper from the lab
2. At home place it in a small jar (like a marmalade or salsa jar) and carefully pour about 20 ml of white or rice vinegar. The volume of vinegar (Acetic Acid) should be about 1/10 of the total volume of your jar
3. Seal the container and observe it every day for a week. Write down your observations in the table below and take a photograph to upload along with each day’s observations
4. Bring to class next week.
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Date |
Insert photograph |
Observations |
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Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Continue as needed |
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1) Give the chemical formula for Verdigris
2) Give the chemical name for Verdigris
3) Why do you only use a small amount of acetic acid and a large amount of copper metal to prepare this pigment?)
4) Is Verdigris a stable pigment? Explain your answer
5) Give two examples of the use of Verdigris in an artwork
6) What element is responsible for the color of Verdigris
7) Give a brief history (paragraph long at least) of the use of Verdigris through time
2024-03-08