<p>Mock Exam III CH115 Dr. Hamilton</p><p>1. Which picture best represents the hydroxide ion in solution?</p><p>2. How many moles of atoms of O in 3 moles? a) 2.1 x 1025 b) 1.8 x 1024 c) 2.1 x 10-25 d) 5.0 x 10-24</p><p>3. Compute the percentage of C in the oxalate ion. a) 13.6% b) 72.7% c) 18.2 % d) 27.3%</p><p>4. A molecule has an empirical formula of C3H6O2. If the molar mass of the compound is determined to be 370 g/mol, what is the compound? a) C3H6O2 b) C9H16O2 c) C15H30O10 d) C30H60O20</p><p>5. From problem 4, how many atoms of the compound do you have if you start with 74 grams of it? a) 1.65 x 1028 b) 1.65 x 1032 c) 6.022 x 1023 d) 1.20 x 1023</p><p>6. Which of these is not a compound with the empirical formula CH5ON3S2? a) C2H10ON6S4 b) CH5ON3S2 c) C100H500O100N300S200 d) C9H45O9N27S18</p><p>7. The reaction NaOH + HBr  NaBr + H2O in lab yields only 88% yield. If 20 grams of NaOH and 25 grams of HBr react, how much NaBr is formed in grams? a) 22.5 b) 45 c) 32 d) 23</p><p>8. What is the theoretical yield of NaBr? a) 22.5 g b) 20.33 g c) 25.66 g d) 36.25 g 9. In principle one could use only the non-global warming part of natural gas, H2, via CH4 (g) → C (s) + 2 H2 (g).What classification of reaction is this? a) decomposition b) combustion c) single displacement d) double displacement</p><p>10. What is the oxidation number oxygen in KO2? a) 0 b) -1/2 c) -1 d) -2</p><p>11. In the reaction between calcium hydroxide and barium sulfate, what is the precipitate formed? a) calcium ions b) hydroxide ions c) calcium sulfate d) barium hydroxide</p><p>12. What is the oxidation number of phosphorus in H3PO4? a) -1 b) 1 c) 3 d) 5</p><p>13. What are the spectator ions in this unbalanced equation? KOH + H2SO4  K2SO4 + H2O. a) water b) OH-, H+ + 2- c) K , SO4 d) K+, H+</p><p>14. What is the balanced equation from left to right in the equation above. a) 1, 2, 1, 2 b) 2, 1, 2, 1 c) 2, 1, 1, 2 d) 1, 2, 2, 1</p><p>15. In the combustion of 2-methylbutane, 10 grams of water is formed. How much CO2 is formed? a) 10 g b) 15 g c) 20 g d) 25 g Use this table to answer questions 16-18.</p><p>16. Will the reaction occur? If yes, how many electrons are transferred? Co + Mg2+  Co2+ + Mg. a) no b) yes, 1 c) yes, 2 d) yes, 3</p><p>17. Will this reaction occur? If yes, how many electrons are transferred? Mn + 2H2O(g)  Mn(OH)2 + H2(g) a) no b) yes, 1 c) yes, 2 d) yes, 3</p><p>18. Will this reaction occur? What molecule is reduced? Ni + H2SO4  NiSO4 + H2(g) a) no b) yes, Ni c) yes, H2SO4 d) yes, H2</p><p>- 19. How many resonance structures does NO3 have? a) 4 b) 3 c) 2 d) 0</p><p>20. In this reaction, what is the reducing agent? Fe2O3 + 3CO  2Fe + 3CO2 a) Fe2O3 b) CO c) Fe d) CO2 Short Answer</p><p>1. Balance these equations (include states of matter for part a and d). a) </p><p> b) </p><p> c) </p><p> d) </p><p>2. Look at part 1c. Assign oxidation numbers to each atom and then label which is the reducing agent and which is the oxidizing agent.</p><p>3. In the combustion of 20 grams of octene with 15 grams of oxygen, 4 grams of carbon dioxide is produced. What is the percent yield and how many atoms of excess reagent is left over after the reaction goes through completion? </p>