Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CCST105 Summer 2013 Final Exam Name: ________________________ Final Exam The Chemistry of CSI (200 points) You will only need a pen or a pencil and a calculator to finish this exam You are encouraged to look over the entire exam before beginning to write your answers YOU MUST SHOW WORK FOR ALL CALCULATIONS Problem I A First Look at Forensic Chemistry (50 points) II Chemical Reactivity and Molecular Shapes (50 points) III Aqueous Chemistry (50 points) IV Forensic Chemistry (60 points) Total: (200 points) Score I A First Look at Forensic Chemistry Consider the compound arsenic (III) oxide, (As2O3), which is typically used in poisonings a) What are the elements and how many of each are present in arsenic (III) oxide b) What is the molecular weight of arsenic (III) oxide? 3. Write the electronic configuration for the element elements phosphorous and magnesium 4. Write the answer to the following mathematical problems with the correct number of significant figures: 40.99 +17.60 + 12.10 = 9.0 X 3.00 x 212 = 5. Chlorine is important to our everyday life. The element undergoes extensive reactions in nature making both ionic and covalent compounds. (8 points) a) What is the definition of an ionic compound and provide an example of an ionic compound that contains chlorine. b) What is the definition of a covalent compound and provide an example of a covalent compound that contains chlorine. 6. Potassium chlorate KClO3 is used as an explosive in fireworks. Balance the following chemical equation for the decomposition of potassium chlorate: KClO3 O2 + KCl 7. The Haber process is responsible for most of the ammonia (NH3) production in the world : N2 + 3H2 2NH3 If you have an excess of N2 and 8g of H2 in the reaction, how much ammonia would you make (in grams)? II Chemical Reactivity and Molecular Shapes 1. Provide the shape for the following molecules: 3. Name the following compounds: NaCl SiO2 N2O5 CoCl3 4. Give the chemical formulas of the following compounds: vanadium(III) iodide dichlorine heptoxide carbon nitride III. Aqueous Solutions 1. What is the range of the pH scale and what pH is basic? 2. Your blood is made up of a HCO3:CO2 buffer system. What does a buffer system do and why is it important for your blood? 3. Europium chloride hexahydrate EuCl3. 6H2O is used to prepare a dye that used to visualize fingerprints detected using fuming superglue. The solution is made by adding 1.00g of europium chloride in 800 mL. What is the molarity of the solution? Hint: the water is part of the chemical formula and must be included in the weight. 4 If 10 mL of the solution in 2 is diluted to 950 mL, what is its new molarity? 5. Why is molecular shape important when considering the interactions of drugs and the body? 6. Rank the following solutions in order of increasing boiling point. Explain your reasoning 0.1 M (HN4)2SO4 0.2 M CuSO4 0.15 M KI 7 . Define osmosis and describe what happens to red blood cells if they are placed in a hypertonic solution IV Forensic Chemistry 1. Blood spatter can provide critical evidence in where things were during the commission of a crime. How can blood spatter help determine what happened at a crime scene? Consider this sample blood drop from what direction did the blood originate? How could you figure out the angle of impact? 2. Why is the size of the sample collected not as important when collecting a homogeneous sample from a crime scene? Why are their guidelines for sample collection in forensics? 3. It requires approximately 2700 accumulated degree hours (ADH) for a species of blow fly to become 14 mm maggots. Assume that this species is the first to deposit eggs on a body. Determine the time of death of a body discovered at 5 A.M. (with 14 mm maggots) in an apartment with the thermostat set at 62oF. 4. How is forensic entomology used in determining the time of death? What factors must be considered? 5. Explain, briefly, rigor mortis, algor mortis and livor mortis. 6. How does psychology play a role in solving crimes? 7. What is the percent of the general population that has a 12,12 pattern on TPOX and a 8,14 pattern on D16S539? How many people would you need to find this pattern? 8. Consider the DNA sequence [GACAAAAAC]. what amino acids does this sequence code for? Hint go to the formula sheet, Find table 14.2 and use the fact every three letters in the sequence code for an amino acid 9. Explain how an immunoassay works 10 Describe two other forensics techniques that we learned about this semester BONUS: 8. (Difficult!) A body was discovered on January 3rd at 10:00 am . The average temperature in the area was as follows Jan 3rd 50 oF Jan 2nd 65 oF Jan 1st 63 oF Dec 25th –Dec 31st 55 oF. 14 mm maggots (3rd stage) of the blow fly were discovered on the body, what is the approximate time of death? It takes 72 hours at 70 oF to reach the 14 mm maggot stage. Useful Formulas and Constants Physical Constants: Speed of light (vacuum) c 3.00 X108 m/s Plank’s constant h 6.62 x 10-34 J·s Mass of a proton p 1.0073 amu Mass of a neutron n 1.0087 amu Mass of an electron e- 0.005486 amu Equations: c= E = h V1 = M2V2 Tfreezing = iKfm pH = - log[H+] Common Polyatomic Ions: CN- Cyanide SO42- Sulfate NO3- Nitrate Strong Acids HCl Hydrochloric H2SO4 Sulfuric HNO3 Nitric Conversion Factors: 1Mx = 1kx = 1x = 1mx = 1x = x = s, g or m 1000 kx 1000 x 1000 mx 1000 x 1000 nx Visible light colors and wavelengths: violet blue green 380–450 nm 450–495 nm 495–570 nm yellow orange red 570–590 nm 590–620 nm 620–750 nm Tboiling = iKbm