Lecture 02 Chemistry

Lecture 02 Chemistry - Fundamentals of Micromachining...

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Unformatted text preview: Fundamentals of Micromachining Properties of Micromachining Chemicals Be Careful and Know Some Chemistry On April 16, 1947, 2200 tons of ammonium nitrate [fertilizer] was stored on board the S. S. Grandcamp along with 1500 tons of fuel oil. While docked at Texas City, Texas, a fire was detected in the hold. An order was given to close hatches and to apply steam throughout the hold. Under these conditions, the fire could not extinguish. Instead, the internal pressure built up at an uncontrollable rate, causing the cargo vessel to explode. Six hundred people were killed and another 3500 were injured. The property damage was comparable to that experienced during a major wartime bombing incident. The total property loss was estimated as $33 million based upon 1947 costs. Eugene Meyer, The Chemistry of Hazardous Materials , 2nd ed. Sulfuric Acid (H 2 SO 4 ) - 1 most commonly used industrial chemical also called oil of vitriol colorless, oily, syrupy liquid, specific gravity = 1.84 standard reagent concentration is 98 %, yellow bottle cap NFPA704M code = 3-0-2-W fuming sulfuric acid or oleum has additional SO 3 dissolved into solution; actually is H 2 S 2 O 7 , disulfuric acid primary hazards: when dissolved into water, H 2 SO 4 liberates considerable heat 20 kcal/mol = 1570.9 J/cm 3 H 2 SO 4 is a strong acid, but only the first proton dissociates completely; second proton has K i = 10-2 always add acid to water to avoid spattering Sulfuric Acid (H 2 SO 4 ) - 2 primary hazards: concentrated H 2 SO 4 has a great affinity for H 2 O: hygroscopic concentrated H 2 SO 4 will dehydrate sugars, starches, and cellulose acid burns to skin dehydrate the tissue with localized evolution of heat. skin becomes charred, like burnt wood concentrated H 2 SO 4 dehydrates concentrated HClO 4 (perchloric acid). The two can explosively decompose and must be stored in separate cabinets. concentrated H 2 SO 4 can react to form hazardous compounds chlorine containing oxidizers will react explosively will decompose salts into other acids 2NaF + H 2 SO 4 Na 2 SO 4 + 2HF may produce toxic gases, e.g. Br 2 , I 2 , SO 2 , CO, COS, H 2 S concentrated H 2 SO 4 will oxidize carbon, lead, and copper Nitric Acid (HNO 3 ) - 1 second most commonly used industrial chemical colorless liquid, often reddish-brown from dissolved NO 2 light exposure produces: 4HNO 3 4NO 2 + 2H 2 O + O 2 also called aqua fortis in art engraving excess dissolved NO...
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This note was uploaded on 11/16/2011 for the course MSE 5960 taught by Professor Douglas during the Fall '04 term at University of Florida.

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Lecture 02 Chemistry - Fundamentals of Micromachining...

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