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Types of Reactions in Art and Artists’ Materials Fall 2014

Types of Reactions in Art and Artists’ Materials Fall 2014. Double Replacement. Producing Acid-Free Paper Wood pulp has natural acids; during production, acid-free paper may be treated with a mild base -usually calcium or magnesium carbonate -

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Types of Reactions in Art and Artists’ Materials Fall 2014

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  1. Types of Reactions in Art and Artists’ MaterialsFall 2014

  2. Double Replacement Producing Acid-Free Paper Wood pulp has natural acids; during production, acid-free paper may be treated with a mild base -usually calcium or magnesium carbonate - which neutralizes the acids and prevents the formation of additional acids. H2SO3 + CaCO3 CaSO3 + H2O + CO2 http://www.catalogs.com/info/technology/what-is-acid-free-paper.html

  3. Paper Making Continued Much of the commercially produced paper today is acid-free. This is not due to the neutralizers added, but is largely the result of a shift from china clay to chalk as the main filler material in the pulp. Chalk is cheaper. It also reacts with acids and requires the pulp to be chemically neutral or alkaline. china clay http://www.catalogs.com/info/technology/what-is-acid-free-paper.html

  4. Paper Manufacturing Process:

  5. Paper Making Continued Another feature is sizing. Paper can absorb ink. Sizing is used on fibers in order to reduce their tendency to absorb liquids; so ink stays on the surface of the paper, instead of being absorbed. The sizing additives mixed with the pulp must also be acid-free. Until 1980 mainly a rosin in combination with alum was used. When the paper industry started using chalk instead of china clay as filler, the paper chemistry had to switch to a neutral process. Today mainly AKD (alkyl ketene dimer) and ASA (alkenyl succinic anhydride) are used.

  6. More Double Replacement When acids in acid rain react with the stone/rock in statues, salt, water, and carbon dioxide are formed: H2SO4 + CaCO3 CaSO4 + H2CO3 then H2CO3  H2O + CO2 Marble statues are made of calcium carbonate. • When carbon dioxide and sulfur dioxide are in the air as pollutants, paintings can be damaged. • Some solid precipitates from double replacement reactions are used as pigments.

  7. Single Replacement • Rust gets its brick-red color from iron (III) oxide, Fe2O3: • Fe + H2O  Fe2O3 + H2

  8. Synthesis • Using acids to help egg dye adhere to eggs

  9. Synthesis continued • Copper patina: 2Cu + O2 Cu2O then 2CuO + CO2 + H2O  Cu2CO3(OH)2(green↓) • Plating metals on jewelry

  10. Copper Patina (Why it turns green!) Patina on statues (most notably the Statue of Liberty [1]) is made of copper sheet: "The formation of patina varies with atmospheric conditions and may not even form in exceedingly dry conditions. Typically however, the “Statue of Liberty" tint does not make its entrance until around the 15th year or later. [2]” Sources: [1] http://www.unc.edu/~jnrandal/sol.pdf [2] http://www.copperliquidpaint.com/Copper

  11. Copper Patina Continued “The composition of patina varies dramatically with location and may contain significant amounts of copper sulfate (CuSO4). One investigation (1932 [3]) of a 13 year old marine specimen found a composition of the patina to be (CuSO4) 2.5%, copper carbonate (CuCO3) 12.8% and copper hydroxide (Cu(OH)2) 52.5%.“ Source:[3] Handbook of Copper Compounds and Applications, H. W. Richardson, ed., CRC Press, Boca Raton, FL 1997, p 156.

  12. Synthesis • Para red dye is used in the making of American flags. • The final step of the reaction involves a “coupling” reaction with either an amino containing aromatic ring or an alcohol-containing aromatic ring (phenol – aromatic ring with a hydroxyl group). For example, we can take the diazonium salt from p-nitroaniline and base-treated 2-naphthol and form para red. • Figure 7: Synthesis of para red from p-nitroaniline and 2-naphthol.

  13. Combustion • Using a torch in welding • Using an oven in glass blowing • Wood burning

  14. Decomposition • Sunlight breaks bonds in color molecules, causing them to fade. • Concrete is a durable building material for sidewalks, paths and driveways. The pitted surface of concrete can collect debris such as those from fallen leaves. As the leaves decompose, they may leach plant dyes and stain the concrete's surface. Carbohydrates in the leaves break down, aiding in the carbon cycle. C6H12O6 CO2 + dye http://www.fs.fed.us/wildflowers/ethnobotany/dyes.shtml • Several dyes are obtained naturally from plants decomposing:

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