CU CHM 203 - General Chemistry Exam

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Exam TwoCHM 203 (Dr. Mattson)26 September 2005Academic Integrity Pledge:In keeping with Creighton University’s ideals and with the Academic Integrity Codeadopted by the College of Arts and Sciences, I pledge that this work is my own and thatI have neither given nor received inappropriate assistance in preparing it.Signature:Instructions: Show all work whenever a calculation is required! You will receive credit for how you worked each problem aswell as for the correct answer. This exam is worth 50 points. BOX YOUR ANSWERS!1. (3 pts) Determine the number of moles ofcalcium hydroxide present in a 14.55 g sample.2. (3 pts) How many moles of fluorine atoms, F,are present in 55.9 g carbon tetrafluoride?3. (3 pts) Use Avogadro’s number to determinethe actual number of platinum atoms, Pt,present in a filament of platinum with a massof 75.3 µg.4. (3 points) Balance the following equation withthe smallest whole number coefficients.C3H6Cl2 + O2 €  →  CO2 + H2O + HCl5. (3 pts) Calcium chloride reacts with sodiumphosphide to produce calcium phosphide andsodium chloride. Balance the equation for thisreaction.6. (3 pts) What mass of F2 is needed to reactcompletely with 14.3 g gold?3 F2 + 2 Au €  →  2 AuF37. (3 pts) Consider the following balancedequation:As2S3 + 14 Cl2 + 20 H2O €  →  2 H3AsO4 + 3 H2SO4 + 28 HClSuppose 40.0 g As2S3, 150 g Cl2, and 65 g H2Owere allowed to react according to the equation.Determine the limiting reagent. [MM(g/mol):As2S3 = 246.1; Cl2 = 70.9; H2O = 18.0]As2S3 + 14 Cl2 + 20 H2O €  →  products8. Again refer to the chemical equation in theprevious problem. If 175 g Cl2 were allowed toreact with excess As2S3 and H2O according tothe equation given,(a) (3 pts) determine the theoretical yield ofH3AsO4. [MM: H3AsO4 = 141.94 g/mol](b) (3 pts) determine the percent yield of H3AsO4 ifthe actual yield were 46 g H3AsO4.9. (4 pts) In thereaction shown, is A and is B.What is thereagent in excessand what is thebalanced equation?Think!excessBalanced equationA.A2A2 + 3 B2€  →  2 AB3B.B2A2 + 3 B2€  →  2 AB3C.A24 A2 + 10 B2€  →  6 AB3 + 2 B2D.B24 A2 + 10 B2€  →  6 AB3 + 2 B2E.none4 A2 + 10 B2€  →  6 AB3 + 2 B210. (3 pts) What is the molarity of a solutionprepared by dissolving 40.0 g potassium iodidein water to make 750.0 mL solution?[MM(g/mol): KI = 166.0]11. (4 pts) A compound of nickel, phoshorus, andoxygen contains 48.11% Ni, 16.92% P, and therest 0. What is the formula for the compound?A. Ni2P3O4B. Ni3P2O4C. Ni3P2O8D. Ni2P3O8E. NiP3O6Show work here12. (2 pts) The simplest formula of a substance isfound to be C2H1Cl1, and its molar mass isfound by experiment to be approximately 180g·mol–1. What is its exact molar mass?A. 60.5 g·mol–1B. 180.0 g·mol–1C. 121.0 g·mol–1D. 181.4 g·mol–1E. 241.9 g·mol–1Show work here13. (10 pts) Circle each of the following as either“I” for ionic, “CM” for covalent molecular or “A”for acidic or “E” for element. Then determine ifeach is properly named. If it is, circle Ok; if not,circle Not.Circle:Printed Name:Circle:CaF2I CM A Ecalcium difluorideOk NotFeSO4I CM A Eiron sulfateOk NotP2O5I CM A Ephosphorus oxideOk NotH2SO4I CM A Esulfuric acidOk NotKClO3I CM A Epotassium chlorateOk NotN2I CM A EnitrogenOk NotHBrO2I CM A Ebromous acidOk NotHIO3I CM A Eiodic acidOk NotNa3PO4I CM A Etrisodium phosphateOk NotLi3AsI CM A Elithium arsenideOk Not14. (BONUS! 1 point) Print your name here:Your exam score (50 possible): Determine your grade:A > 46.5; B+ > 43.5; B > 41.0;C+ > 37.5; C > 34.00; D > 30.00Answers:1. 0.196 mol Ca(OH)22. 2.54 mol of F3. 2.32 x 1017 Pt atoms4. C3H6Cl2 + 4 O2 €  →  3 CO2 + 2 H2O + 2 HCl5. 3 CaCl2 + 2 Na3P €  →  Ca3P2 + 6 NaCl6. 4.14 g F27. Cl28. (a) 50.0 g H3AsO4 (b) 92 %9. B10. 0.321 M KI11. C12. D13. Correct answers in redCircle:Printed Name:Circle:CaF2I CM A Ecalcium difluorideOk NotFeSO4I CM A Eiron sulfateOk NotP2O5I CM A Ephosphorus oxideOk NotH2SO4I CM A Esulfuric acidOk NotKClO3I CM A Epotassium chlorateOk NotN2I CM A EnitrogenOk NotHBrO2I CM A Ebromous acidOk NotHIO3I CM A Eiodic acidOk NotNa3PO4I CM A Etrisodium phosphateOk NotLi3AsI CM A Elithium arsenideOk


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CU CHM 203 - General Chemistry Exam

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