142A_Exam1B_071511 - Chem 142 VERSION B Summer 2011 CHEM...

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Unformatted text preview: Chem 142 VERSION B Summer 2011 CHEM 142 - Exam 1 Version B !!! DO NOT OPEN THIS EXAM BOOK UNTIL TOLD TO DO SO BY THE INSTRUCTOR !!! Instructor: Dr. Kari Pederson NO GRAPHING CALCULATORS ALLOWED Date: Time: Friday, July 15 9:40-10:40am NO HEADPHONES ALLOWED (EARPLUGS ARE OK) Location: BAG 154 NO HATS WITH BRIMS ALLOWED ONLY CALCULATORS MAY BE USED AS CALCULATORS (you may not use your cellular phone as a calculator) !!! PLEASE READ THIS !!! Indicate all of the following on your scantron form or five points will be deducted from your exam score: First Name, Last Name, Student Number, Section, Exam Version YOUR FULL NAME: _______________________ first name ________________________ discussion section ________________________ last name ________________________ seat number YOUR SECTION/SEAT: EXAM 1 VERSION B Page 1 of 9 Chem 142 VERSION B Points Possible 24 40 16 20 -5 100 Score Summer 2011 Question 1-8 9-16 17-20 21 Scantron Info? TOTAL EXAM 1 VERSION B Page 2 of 9 Chem 142 VERSION B Summer 2011 MULTIPLE CHOICE: CONCEPTS. 8 @ 3 pts each 24 POINTS TOTAL Please mark the one correct answer for each of the following questions on your scantron. 1. Which of the following is a physical property of the element chlorine? A) Chlorine is a gas that is poisonous if inhaled . B) Chlorine will react with sodium to make salt. C) Chlorine is a gas that will become a liquid at 34.4 C. D) Chlorine is used in water treatment as a disinfectant. E) Chlorine exists as a diatomic molecule. Which metric prefix symbol means 1 x 10-3? A) p B) m C) M D) k E) n As chemists and other scientists seek to understand the principles that govern nature they employ what is called the scientific method. The first step in this method is ____. A) the proposal of a hypothesis B) the testing of a scientific law C) the making of observations D) the application for a research grant E) the testing of a hypothesis Reaction of 10.0 grams of calcium with _________________ of sulfur gave 22.0 grams of calcium sulfide. All the calcium was used, but there were 20.0 grams of sulfur left over. A) 12.0 grams B) 22.0 grams C) 32.0 grams D) 42.0 grams E) none of the above Of the following, only _______________ would not be classified as a pure substance. A) sucrose B) acetic acid C) oxygen D) a granite rock E) water 2. 3. 4. 5. EXAM 1 VERSION B Page 3 of 9 Chem 142 6. VERSION B Summer 2011 Which statement best describes isotopes? A) atoms in the same vertical group B) atoms with the same number of neutrons and different numbers of protons C) atoms with the same number of protons and different numbers of neutrons D) atoms with the same numbers of protons and neutrons E) atoms in the same horizontal period The element ______________ is classified as a metal whereas _______________ is classified as a metalloid. A) Sr, Ge B) Ni, Ba C) As, Sb D) Br, Si E) Rb, I In an atom of A) B) C) D) E) 65 30 7. 8. Zn __________. the number of protons equals the number of neutrons 30 electrons are found outside the nucleus 35 protons are found in the nucleus the total number of electrons and protons equals 65 30 neutrons are found in the nucleus EXAM 1 VERSION B Page 4 of 9 Chem 142 VERSION B Summer 2011 MULTIPLE CHOICE: SHORT CALCULATIONS. 8 @ 5 pts each 40 TOTAL POINTS Please mark the one correct answer for each of the following questions on your scantron. 9. The volume of a ball bearing is 1.37 mm3. What is its volume in cubic centimeters (cm3)? A) 1.37 x 103 cm3 B) 1.37 x 101 cm3 C) 1.37 x 10-1 cm3 D) 1.37 x 10-3 cm3 E) none of the above 10. A sugar contains 42.14% C, 6.48% H and 51.46% O. What is the molecular formula of the sugar if its molar mass is approximately 330 g/mol? A) C11H22O11 B) C13H2O16 C) C20H20O17 D) CH2O E) none of the above 11. Calculate the moles of calcium ions present in a milliliter of 0.265 M calcium sulfate. A) 2.65 x 10-1 moles B) 5.30 x 10-1 moles C) 2.65 x 10-4 moles D) 5.30 x 10-4 moles E) none of the above 12. A stock solution of potassium dichromate, K2CrO4, is made by dissolving 76.2 g of the compound in 1.00 L of solution. How many milliliters of this solution are required to prepare 1.00 L of 0.100 M K2CrO4? A) 392 mL B) 255 mL C) 76.2 mL D) 39.2 mL E) none of the above 13. Calculate the number of lithium ions in 21.4 mg of lithium nitride. A) 3.70 x 1026 ions B) 4.62 x 1020 ions C) 6.15 x 1020 ions D) 3.70 x 1020 ions E) none of the above EXAM 1 VERSION B Page 5 of 9 Chem 142 VERSION B Summer 2011 14. What is the mass % of H in ammonium hydrogen sulfate (NH4HSO4)? A) 0.9% B) 3.5% C) 4.4% D) 12% E) none of the above 15. Naturally occurring copper (63.546 amu) is composed of two isotopes, copper-63 (62.916 amu) and copper-65 (64.955 amu). From this, one can conclude that naturally occurring copper is composed of ________________. A) approximately 20% copper-63 and 80% copper-65 B) approximately 80% copper-63 and 20% copper-65 C) approximately 30% copper-63 and 70% copper-65 D) approximately 70% copper-63 and 30% copper-65 E) none of the above 16. What is the correct name of Pb(ClO4)2? A) lead(II) perchlorate B) lead(IV) perchlorate C) lead(II) chlorate D) lead(IV) chlorate E) lead(II) chlorite EXAM 1 VERSION B Page 6 of 9 Chem 142 VERSION B Summer 2011 MATCHING. 8 @ 2 pts each 16 POINTS TOTAL Please indicate the letter of the one correct answer for each of the following questions in the blank. 17. The conversion of CO (g) into CO2 (g) is an example of a ______ change/reaction. 18. Give the chemical symbol/name (whichever is missing) for each of the following elements: A) S _______ B) Boron _______ C) Na _______ D) Ni _______ E) Iron ________ 19. Reaction of 5.80 grams of aluminum with 4.80 grams of oxygen gives 10.20 grams of aluminum oxide with 0.40 grams of aluminum left over. This illustrates the Law of _____________________. 20. The number of _______ is equal to the number of electrons in a neutral atom. A) E) I) M) Q) U) X) Physical B) Calcium F) Protons J) Sodium N) Nickel R) Neutrons V) Multiple Proportions K C) Chemical D) Os Electrons G) Nitrogen H) I B K) Decomposition L) Fe Ir O) Sulfur P) In P S) Carbon T) O Lead W) Br Y) Definite Proportions Z) Conservation of Mass EXAM 1 VERSION B Page 7 of 9 Chem 142 VERSION B Summer 2011 LONG ANSWER. 20 POINTS TOTAL 21. In lab, a student mixes 8.0 mL aqueous solutions of sodium sulfide (4.0 M) and copper(III) chloride (2.5 M) are mixed together. A) What is the net ionic equation for this reaction? (3 pts) Please use your answer from part A for the calculations in parts B-D. If you are unable to write the balanced net ionic equation or no precipitate would form in this reaction (i.e., no reaction would occur), use the following information for the remainder of the problem: 75. mL of 0.40 M iron(III) chloride solution and 60.0 mL of 5.0 M ammonium sulfide solution are mixed in order to precipitate iron(III) sulfide according to the following balanced net ionic equation: 2Fe3+ (aq) + 3S2- (aq) Fe2S3 (s) B) Assuming the reaction goes to completion, what mass of precipitate will form? (6 pts) EXAM 1 VERSION B Page 8 of 9 Chem 142 VERSION B Summer 2011 C) What mass of each excess ion will remain? (9 pts) D) If the student recovers 2.00 g of precipitate, what is the percent yield? (If you did not calculate a theoretical yield in part B, use 3.53 g here) (2 pts) EXAM 1 VERSION B Page 9 of 9 ...
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