CHEM 10113, Exam 1 September 19, 2006

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1 CHEM 10113, Exam 1 September 19, 2006 Name (please print) All answers must use the correct number of significant figures, and must show units! 1. (15 points) Mercury poisoning is a debilitating disease that can be fatal. If the amount of mercury in a polluted lake is 0.40 g Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface area of 125 mi 2 and an average depth of 22 ft.) 2. (10 points) In the following organic compounds, identify each of the boxed functional groups by writing the appropriate family name (i.e. ketone, alkene, etc) next to each box. (Each unlabeled corner is part of a carbon chain.)

2 3. (8 points) The isotope of an element, X, has a mass number of 79. The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium having a formula of Na 2 X. Which of the following statements is/are true? For the false statements, correct them. a. The binary compound formed between X and fluorine will be a covalent compound. b. The isotope of X contains 38 protons. c. The isotope of X contains 41 neutrons. d. The identity of X is strontium, Sr. 4. (8 points) Balance the following equations. Ag (s) + S 8(s) Ag 2 S (s) Li (s) + H 2 O (l) LiOH (s) + H 2(g) 5. (12 points) SHOW ALL WORK. Protactinium (Pa), a highly toxic metal, is one of the rarest and most expensive elements. The following reaction is one method for its preparation: 2 PaI 5(s) 2 Pa (s) + 5 I 2(s) a) Given 15.8 mg of reactant, how many milligrams of protactinium could be synthesized? b) If 3.4 mg of Pa was actually obtained, what was the percent yield of this reaction? c) If you obtained 3.4 mg of Pa and the percent yield was 78.6%, how many grams of PaI 5 were used in the preparation?

3 6. (15 points) Name the following compounds. Cr 2 (HPO 4 ) 3 BaO CS 2 XeF 4 HNO 2 7. (15 points) SHOW ALL WORK. In a quantitative analysis study, g of a compound containing carbon, hydrogen and oxygen only yielded 2.01 g of CO 2 and g of H 2 O in a combustion analysis apparatus. Determine the empirical formula of the compound. (MM CO 2 = 44.0 g/mol, MM H 2 O = g/mol)

4 8. (17 points) Match words from the following selection with the statements below. The same word may be used more than once, and not all words have to be used. All correct answers must be included to receive full credit! strontium disulfur dichloride iodine germanium hafnium calcium rubidium oxide decomposition temperature volume is from the same period as tin in the periodic table. is a molecular compound. Is an example of an intensive property. is a metalloid. is an example of a chemical property. is a binary compound. has a high boiling point. 9. (9 points) Briefly define the following terms. a.) hydrate: b.) solubility: c.) potential energy: 10. (8 points) SHOW ALL WORK. Phosphorus pentachloride reacts with water to give phosphoric acid and hydrogen chloride according to the the following equation: PCl 5(s) + 4 H 2 O (l) H 3 PO 4(l) + 5 HCl (g) In one experiment, mol of PCl 5 was slowly added to 2.06 mol of water. a) What reactant, if either, was the limiting reactant? b) How many grams of HCl were formed in the reaction?

5 11. (6 points) Complete the calculations, and report your answers using scientific notation, and the correct number of significant figures. a g g = b. (2.83 x 10 5 g) / (413.1 L) g/l = 12. (18 points) Write chemical formulas for each of the following. propane sulfur dioxide hydrogen cyanide cobalt(iii) sulfide copper(i) sulfate pentahydrate chlorous acid 13. (3 points) The hallucinogenic drug LSD has the molecular formula C 20 H 25 N 3 O. One suspected sample contained 64.88% C, 5.95% H, and 9.46% N. What is the percentage O in the sample? 14. (3 points) A certain hydrocarbon is composed entirely of C and H. In 4 mol of the compound there are 12 mol of C; in 6 molecules of the compound, there are 48 atoms of H. What is the empirical formula of the compound? 15. (3 points) Give the empirical formula of tetraarsenic decasulfide.

6 CHEM 10113, Exam 1 September 19, 2006 Name (please print) All answers must use the correct number of significant figures, and must show units! 1. (15 points) Mercury poisoning is a debilitating disease that can be fatal. If the amount of mercury in a polluted lake is 0.52 g Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface area of 111 mi 2 and an average depth of 19 ft.) 2. (10 points) In the following organic compounds, identify each of the functional groups by writing the appropriate family name (i.e. ketone, alkene, etc) next to each box. Each unlabeled corner is part of a carbon chain.

7 3. (8 points) The isotope of an element, X, has a mass number of 79. The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium having a formula of Na 2 X. Which of the following statements is/are true? For the false statements, correct them. a. The isotope of X contains 41 neutrons. b. The isotope of X contains 38 protons. c. The identity of X is strontium, Sr. d. The binary compound formed between X and fluorine will be a covalent compound. 4. (8 points) Balance the following equations. Na 2 CO 3 + Mg(NO 3 ) 2 MgCO 3 + NaNO 3 C 4 H 10 O 2 + O 2 CO 2 + H 2 O 5. (12 points) SHOW ALL WORK. Protactinium (Pa), a highly toxic metal, is one of the rarest and most expensive elements. The following reaction is one method for its preparation: 2 PaI 5(s) 2 Pa (s) + 5 I 2(s) a) Given 35.7 mg of reactant, how many milligrams of protactinium could be synthesized? b) If 7.2 mg of Pa was actually obtained, what was the percent yield of this reaction? c) If you obtained 7.2 mg of Pa and the percent yield was 82.5%, how many grams of PaI 5 were used in the preparation?

8 6. (15 points) Name the following compounds. SO 3 Na 2 SO 3 Mn 2 S 3 PI 3 HClO 2 7. (15 points) SHOW ALL WORK. In a quantitative analysis study, g of a compound containing carbon, hydrogen and oxygen only yielded g of CO 2 and g of H 2 O in a combustion analysis apparatus. Determine the empirical formula of the compound. (MM CO 2 = 44.0 g/mol, MM H 2 O = g/mol)

9 8. (17 points) Match words from the following selection with the statements below. The same word may be used more than once, and not all words have to be used. All correct answers must be included to receive full credit! rubidium disulfur dichloride iron hafnium lead decomposition temperature volume polonium lithium oxide is an element from the same period as tin. is an ionic compound. is an example of an extensive property. is a metal. is an example of a physical property. is a binary compound. has a low boiling point. 9. (9 points) Briefly define the following terms. a.) kinetic energy: b.) decanting: c.) mass spectrometry: 10. (8 points) SHOW ALL WORK. Phosphorus pentachloride reacts with water to give phosphoric acid and hydrogen chloride according to the the following equation: PCl 5(s) + 4 H 2 O (l) H 3 PO 4(l) + 5 HCl (g) In one experiment, mol of PCl 5 was slowly added to 2.32 mol of water. a) What reactant, if either, was the limiting reactant? b) How many grams of HCl were formed in the reaction?

10 11. (6 points) Complete the calculations, and report your answers using scientific notation, and the correct number of significant figures. a) g g = b) (1.43 x 10 5 g) / (43.2 L) g/l = 12. (18 points) Write chemical formulas for each of the following. iron(iii) chloride hexahydrate barium phosphate butane tetraarsenic hexaoxide lead(iv) carbonate phosphoric acid 13. (3 points) The hallucinogenic drug LSD has the molecular formula C 20 H 25 N 3 O. One suspected sample contained 72.07% C, 7.15% H, and 10.88% N. What is the percentage O in the sample? 14. (3 points) A certain hydrocarbon is composed entirely of C and H. In 4 mol of the compound there are 24 mol of C; in 6 molecules of the compound, there are 24 atoms of H. What is the empirical formula of the compound? 15. (3 points) Give the empirical formula of tetraarsenic decasulfide.

11 CHEM 10113, Exam 1 September 19, 2006 Name (please print) All answers must use the correct number of significant figures, and must show units! 1. (15 points) Mercury poisoning is a debilitating disease that can be fatal. If the amount of mercury in a polluted lake is 0.35 g Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface area of 98 mi 2 and an average depth of 19 ft.) 2. (10 points) In the following organic compounds, identify each of the functional groups by writing the appropriate family name (i.e. ketone, alkene, etc) next to each box. Each unlabeled corner is part of a carbon chain.

12 3. (8 points) The isotope of an element, X, has a mass number of 79. The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium having a formula of Na 2 X. Which of the following statements is/are true? For the false statements, correct them. a. The isotope of X contains 38 protons. b. The isotope of X contains 41 neutrons. c. The identity of X is strontium, Sr. d. The binary compound formed between X and fluorine will be a covalent compound. 4. (8 points) Balance the following equations. H 3 PO 4(aq) + NaOH (aq) Na 3 PO 4(aq) + H 2 O (aq) N 2(g) + H 2(g) NH 3(g) 5. (12 points) SHOW ALL WORK. Protactinium (Pa), a highly toxic metal, is one of the rarest and most expensive elements. The following reaction is one method for its preparation: 2 PaI 5(s) 2 Pa (s) + 5 I 2(s) a) Given 12.1 mg of reactant, how many milligrams of protactinium could be synthesized? b) If 2.6 mg of Pa was actually obtained, what was the percent yield of this reaction? c) If you obtained 2.6 mg of Pa and the percent yield was 69.2%, how many grams of PaI 5 were used in the preparation?

13 6. (15 points) Name the following compounds. CuBr B 2 O 3 (NH 4 ) 3 P SF 6 H 2 SO 3 7. (15 points) SHOW ALL WORK. In a quantitative analysis study, g of a compound containing carbon, hydrogen and oxygen only yielded g of CO 2 and g of H 2 O in a combustion analysis apparatus. Determine the empirical formula of the compound. (MM CO 2 = 44.0 g/mol, MM H 2 O = g/mol)

14 8. (17 points) Match words from the following selection with the statements below. The same word may be used more than once, and not all words have to be used. All correct answers must be included to receive full credit! rubidium disulfur dichloride lead iron hafnium decomposition temperature volume sulfur lithium oxide is an element from the same period as titanium. is an ionic compound. is an example of an extensive property. is a nonmetal. is an example of a physical property. is a binary compound. is nonconductive in the solid state. 9. (9 points) Briefly define the following terms. a) mass spectrometry: b) distillation : c) solution: 10. (8 points) SHOW ALL WORK. Phosphorus pentachloride reacts with water to give phosphoric acid and hydrogen chloride according to the the following equation: PCl 5(s) + 4 H 2 O (l) H 3 PO 4(l) + 5 HCl (g) In one experiment, mol of PCl 5 was slowly added to 2.00 mol of water. a) What reactant, if either, was the limiting reactant? b) How many grams of HCl were formed in the reaction?

15 11. (6 points) Complete the calculations, and report your answers using scientific notation, and the correct number of significant figures. a) g g = b) (5.543 x 10 5 g) / (43.2 L) g/l = 12. (18 points) Write chemical formulas for each of the following. mercury(i) dichromate potassium nitrate dinitrogen tetroxide calcium bromide dihydrate pentane acetic acid 13. (3 points) The hallucinogenic drug LSD has the molecular formula C 20 H 25 N 3 O. One suspected sample contained 74.07% C, 7.95% H, and 9.99% N. What is the percentage O in the sample? 14. (3 points) A certain hydrocarbon is composed entirely of C and H. In 4 mol of the compound there are 16 mol of C; in 6 molecules of the compound, there are 24 atoms of H. What is the empirical formula of the compound? 15. (3 points) Give the empirical formula of dinitrogen tetraoxide.