Final Exam Chem 2001 Fall 2022

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Louisiana State University *

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MCKIZILKAY

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Chemistry

Date

Dec 6, 2023

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pdf

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Final Exam, Chem 2001 Name __________________________________________ December 6, 2022 (print clearly) Question 1. (4 pts) Write the dissociation reactions and equilibrium equations for the polyprotic acid H 3 PO 4 Question 2. (4 pts) With UV/Vis measurement, the absorbance at 308 nm measured 0.458 for a 6.00 mg/L cyanide standard, using a 1 cm cuvette. A sample was diluted by adding 0.50 mL of the unknown sample to 9.50 mL of water. Using the same cuvette, the absorbance for the diluted sample measured 0.229 absorbance units measured with the same cuvette. Remember to report the correct number of significant figures . a.) What is the molar extinction coefficient for the standard? b.) What is the final concentration of phosphate for the unknown sample, after multiplying by the dilution factor?

Question 3. (6 pts) a.) List and describe 3 types of analysis that can be accomplished with gas chromatography. (What types of samples can be analyzed?) b.) List and describe 3 types of analysis that can be accomplished with HPLC. (What types of samples can be analyzed?) Question 4. (3 pts) In your new position at Quality Laboratories, you have been requested to set up a lab procedure for the analysis of lead, cadmium, and aluminum in pond water samples. What instrument would you choose for this analysis and why? Question 5. (3 pts) What analytical instrument and detector would you choose for testing low levels of chlorinated hydrocarbons for river water samples? Briefly explain your answer.

Question 6. (3 points) Compare AAS vs ICP, list at least two similarities, and two differences between measurements with an inductively coupled plasma spectrometer (ICP-AES) and an atomic absorption spectrophotometer (AAS). Question 7. (2 points) (Student authored question ) Joe added 20 mL of sample to 600 mL of solvent. What is the dilution factor? Question 8. (3 points) (Student authored question ) What is the percent solids if 25 g of NaCl is added to 75 g of water? Question 9. (3 points) (Student authored question ) What is a buffer?

Question 10. (2 points) (Student authored question ) What happened to the drinking water in Flint Michigan? Question 11. (3 points) (Student authored question ) What is the pH of a solution with pOH of 10? What is the concentration of H + ? Question 12. (8 points) . (Student authored questions ) Famous people. Match the description with the person. Greta Thunberg Mikhail Tswett Rachel Carson Julia Butterfly Hill Joseph Priestly Arnold Beckman Sir Alan Walsh Sir Isaac Newton Alfred Nobel When she was 23, this environmental activist lived in a tree for 738 days! The goal of the “tree - sit” protest was to save the tree and to prevent clear cutting of significant forests. American scientist who invented the pH meter, it was called an acidometer . Australian scientist who invented the atomic absorption spectrophotometer. This person is considered to be the father of physics, invented calculus and formulated the laws of gravity. A Swedish youth activist who started a global movement to advocate for changes in climate policy. Famous quotation “blah blah blah, grownups have failed us.” Known as the father of chromatography, this person invented chromatography while doing research with plant pigments. Author of a book “Silent Spring” which eventually helped ban using the pesticide DDT. Invented dynamite.

Question 13. (3 points) (Student authored question ) What is the pH of a strong acid, HA if the concentration of [OH - ] is 3.97 × 10 -12 ? Student Question 14. (6 points) . (Student authored questions ) Match the event, chemicals or elements of concern for the environment with a description. DDT ( dichlorodiphenyltrichloroethane ) trichlosan Salton Sea PBB (polybrominated biphenyls) melamine Flint, Michigan PCBs (polychlorinated bipiphenyls) thalidomide Love Canal Minimata disease glyphosate Pripyat,Ukraine This molecule is a pesticide which was banned in the United States because it is likely a carcinogen. It has bioaccumulative effects in the food chain, leading to death for fish, birds and wildlife. This controversial antibacterial and antifungal chemical has been used since the 1960s for toothpaste (to prevent gingivitis) and in antibacterial soaps. It is not easily removed by water treatment processes, and emerging studies show that it can be an endocrine disrupter. In 2008, this chemical was added to baby formula to inflate the concentration of nitrogen, to make it seem to have a higher level of protein. Caused kidney stones to develop in 16 children and cause 6 infant deaths in China. Thalidomide was a widely used drug in the late 1950s and early 1960s for the treatment of nausea in pregnant women. It became apparent in the 1960s that thalidomide treatment resulted in severe birth defects in thousands of children. It has two optical isomers which exhibit widely different pharmacological and toxicological effects. Widely used weedkiller, (Roundup) which is controversial because it may cause certain cancers. Also called “dancing cat” disease, produced by eating fish and shellfish contaminated with organic mercury. Mercury poisoning causes neurological problems and eventually, death.

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