CHEM 177 Optional Exam April 24, 2017

Transcription

1 r. Irmi Schewe-Miller r. Robbyn nand This exam consists of questions on 7 pages HM 177 Optional xam pril 24, 2017 Name: Recitation T: Recitation Section: This all-multiple choice question exam will be automatically graded using a bubble sheet. Fill in the corresponding bubbles completely and dark enough to be read by the scanner. The answer you fill in on your bubble sheet is the one that will be scored. You can circle the answer on this exam booklet for your own reference, only. Questions are printed on both sides of each page. The last sheet of the exam contains some useful information and can be used as scratch paper. It must be turned in with your exam! T/Instructor use only. Score: /54 % If you do not correctly bubble-in your ISU I and your recitation section number, your exam score will NOT get uploaded into blackboard gradebook and you will receive a score of 0. o not use mechanical pencils. #2 pencils are highly recommended. Regrade Policy: Graded exam will be returned to you during Thursday recitation. If you have request for regrade, you MUST submit your exam to your T before leaving the recitation room. page 1

2 Optional xam hem 177 S17 ach problem is worth 2 points. Question 1. Which one of the following quantities has 3 significant figures? kg 1500 kj L atm/mol K L Question 2. density mass Which of the following is a chemical property of an unknown sample? Question was removed from grading melting point heat capacity % carbon by mass Question 3. o-60 is used medically for radiation therapy. The nuclei of these isotopes have protons and neutrons. 27, 60 27, 33 27, , , 27 Question 4. The systematic name for SO3(g) is. sulfur oxide monosulfur trioxide sulfur(iii) oxide sulfur trioxide sulfur peroxide Question 5. The correct formula for magnesium phosphide is MgP MnP2 Mg2P Mn2P3 Mg3P2 Question 6. by mass? What is the empirical formula of a compound that contains 29% Na, 41% S, and 30% O NaSO 3 NaSO 2 NaSO Na S O Na2S2O 6 page 3

3 Optional xam hem 177 S17 ach problem is worth 3 points. Question g sample of magnesium nitride (MM g/mol) is reacted with an excess of water. Mg3N2 3H2O 2NH 3 3MgO The actual yield of MgO (MM 40.3 g/mol) is 3.60 g. What is the percent yield in the reaction? 78.7 % 49.4 % 62.5 % 46.6 % 94.5 % Question 8. What are the spectator ions in the reaction between gno3(aq) and Kl(aq)? K + and l g + and NO3 g + and l K + and NO3 NO3 only Question 9. The correct name for HlO4(aq) is. hypochlorous acid chlorous acid hydrochloric acid chloric acid perchloric acid Question 10. Which one of the following is a weak acid? nitric acid perchloric acid hydrobromic acid hydrofluoric acid sulfuric acid Question 11. What is the concentration in mol/l of H 3OH in a solution prepared by dissolving 11.7 g of H 3OH (MM g/mol) in sufficient water to give exactly 230 ml of solution? 11.9 M 1.59 M M M M page 4

4 Optional xam hem 177 S17 ach problem is worth 2 points. Question 12. In which species does nitrogen have the highest oxidation number? NaNO3 NO2 HNO2 N2 NH3 Question 13. The thermochemical equation of the decomposition of methanol is given below: H3OH(l) O(g) 2H 2(g) H = kj/mol How many kj of heat are consumed when 15.5 g of H3OH(l) (MM g/mol) decomposes as shown in the equation? Question 14. alculate the enthalpy of combustion for acetone in kj/mol from the enthalpies of formation given. compound 3H6O(l) O2(g) H2O(l) ΔH f in kj/mol H6O(l) + 4 O2(g) 3 O2(g) + 3 H2O(l) Question 15. The -quantum number(s) determine(s) the orientation of an atomic orbital. principal (n), angular momentum ( ), magnetic, (m ) angular momentum ( ) and spin (m s ) magnetic (m ) and spin (m s ) page 5

5 Optional xam hem 177 S17 ach problem is worth 3 points. Question 16. mole of red photons of wavelength 725 nm has kj of energy xtra redit Question Question 17. The ground-state electron configuration an atom of is [r] 4s2 3d5. V, vanadium Mn, manganese Fe, iron r, chromium a, calcium Question 18. Of the choices below, which gives the correct order of increasing atomic radii? r < l < S < Si < l l < Si < S < l < r S < Si < l < l < r l < S < l < Si < r l < S < l < r < Si Question 19. The reaction of a metal with a nonmetal always produces a(n). oxide ionic compound hydroxide base acid Question 20. What is the electron configuration of an iron(ii) cation, Fe 2+? [r] 4s 2 3d 6 [r] 4s 2 3d 4 [r] 3d 6 [r] 4s 2 4d 6 [Ne] 4s 2 3d 6 xtra redit Question Question 21. ased on the positions of calcium and sulfur in the periodic table, calcium sulfide is expected to be and would have a melting point. ionic, low ionic, high polar covalent, low covalent, low covalent, high page 6

6 Optional xam hem 177 S17 ach problem is worth 2 points. Question 22. In the molecule below, which bond is the most polar bond? F l r I Question 23. How many equivalent resonance forms can be drawn for the carbonate ion, O3 2? (arbon is the central atom.) Question 24. The bond enthalpy () is defined as the enthalpy of reaction in which a covalent bond is broken. xample: l2(g) 2 l(g). ΔHrxn = 242 kj/mol = (l l) reaking bonds is and bond enthalpy is. always endothermic, always positive always exothermic, always positive always endothermic, always negative always exothermic, always negative sometimes endothermic and sometimes exothermic, sometimes positive and sometimes negative Question 25. The molecular geometry of the F 3 molecule is, and this molecule is. trigonal planar, polar trigonal planar, nonpolar trigonal pyramidal, polar trigonal pyramidal, nonpolar T-shaped, nonpolar page 7

7 Optional xam hem 177 S17 ach problem is worth 3 points. Question 26. The molecule shown below has sigma bonds and pi bonds. 4, 3 7, 3 4, 6 10, 0 7, 6 Question 27. What volume (in L) of sulfur dioxide can be produced by the complete reaction of 3.82 g of calcium sulfite (MM g/mol) with excess Hl(aq), when the final SO 2 pressure is 1.09 atm at 44.0? ssume ideal gas behavior. aso ( s) 2Hl( aq) SO ( g) al ( aq) H O( l) Question 28. The molar volume of an ideal gas at STP is L page 8

8 Optional xam hem 177 S17 ach problem is worth 2 points. Question 29. mixture of He, Ne, and r has a total pressure of 6.70 atm. What is the mole fraction of Ne if the partial pressures of He and r are 1.60 atm and 2.80 atm, respectively Question 30. balloon is filled with nitrogen gas at 20. Which one of the following will decrease as the temperature of the balloon is raised to 50 at constant pressure? the average kinetic energy of the molecules the root-mean-square speed of the molecules the strength of the impact of an average molecule with the container wall the density of the gas the volume of the balloon page 9