CHEMISTRY 101 EXAM 3 (FORM A) DR. SIMON NORTH 1. When considering conjugate acids and bases, (2 points) a) Strong acids have strong conjugate bases. b) Strong bases have strong conjugate acids. c) Weak acids have weak conjugate bases. d) Strong bases have weak conjugate acids. e) None of the above is true. 2. What is the normality of a solution prepared by dissolving 4.3 g of HClO 4 in 143 ml of water? (3 points) a) 0.0003 N b) 0.0006 N c) 0.60 N d) 0.30 N e) 0.15 N 3. The bond strength is considerably greater in HF than in the other three hydrogen halides (HCl, HBr, and HI). (1 point) 4. What orbitals make up the pi bond between C and C in H 2 C=CH 2? (5 points) a) 2s on each C b) 2p on each C c) sp 2 on each C d) sp 3 on each C e) none of the above
5. How many of the following statements are true? (5 points) a) 0 b) 1 c) 2 d) 3 e) 4 - Arrhenius acids and bases necessarily make water and a salt when combined. - Acidic aqueous solutions do not conduct electricity. - Acid strengths of most ternary acids containing the same central element decrease with decreasing oxidation state of the central element (i.e. with decreasing number of oxygen atoms). - Strong acids dissociate completely in water - Lewis acids and bases necessarily make water and salt when combined. 6. Given the following equation, (2 points) F - + BF 3 BF 4 - Which of the following statements is true? a) BF 3 is a Lewis acid and F - is a Lewis base b) BF 3 is a Lewis base and F - is a Lewis acid c) BF 3 is an Arrhenius acid and F - is an Arrhenius base d) This is not an acid base reaction e) Only Bronsted-Lowry theory can describe this reaction as an acid-base reaction 7. The following unbalanced reaction takes place in acidic conditions. Cr 2 O 7 2- + Fe 2+ Cr 3+ + Fe 3+ How many moles of electrons are transferred per mole of dichromate reacted? (5 points) a) 5 b) 6 c) 7 d) 8 e) 9
8. According to Lewis Theory, an acid is any species that donates an electron pair. (1 point) 9. In the laboratory a student combines 500.0 ml of a 1.0 M H 3 PO 4 with 500.0 ml of a 1.0 M Ca(OH) 2. (5 points) 2H 3 PO 4 + 3Ca(OH) 2 Ca 3 (PO 4 ) 2 + 6H 2 O What is the final concentration of calcium phosphate? a) 2.0 M b) 0.17 M c) 1.0 M d) 0.25 M e) 0.50 M 10. H 2 CO 3 is a (2 point) a) weak acid b) strong acid c) weak base d) strong base e) soluble salt 11. What are the approximate angles in IBr 2 -? (3 points) a) 30 b) 90 c) 120 d) 109 e) 180
12. When the following unbalanced reaction is balanced under acidic conditions, a) 1 b) 2 c) 3 d) 4 e) 5 MnO 4 - (aq) + C 2 O 4 2- (aq) Mn 2+ (aq) + CO 2(g) what is the stoichiometric coefficient in front of the MnO 4 -? (5 points) 13. The oxidation state of the carbon in the above question changes from (3 points) a) no change in oxidation state b) +3 to 0 c) +3 to +4 d) +4 to 0 e) none of the above 14. 85.0 ml of 0.0650 N H 2 SO 4 solution required 25.25 ml of NaOH solution for neutralization. Calculate the normality and the molarity of the sodium hydroxide solution. (5 points) a) 0.11 M and 0.055 N b) 0.22 M and 0.22 N c) 0.11 M and 0.11 N d) 0.11 M and 0.055 N e) 0.44 M and 0.44 N
15. Pi bonds can be formed between s orbitals. (1 point) 16. In the following reaction, (2 points) NH 3 + H 2 O NH 4 + + OH - Which is the Bronstead-Lowry base? a) NH 3 b) H 2 O c) neither 17. Given the following reaction, 2Rb + H 2 O Rb 2 O + H 2 which of the following statements is true? (5 points) a) Water is the oxidizing agent and Rb is the reducing agent b) Water is being oxidized and Rb is being reduced c) Rb is the oxidizing agent and water is the reducing agent d) b) and c) are correct e) This is not a redox reaction 18. Given that Zn(OH) 2 is amphoteric, which of the following statements is false? (5 points) a) Zn(OH) 2 can react with an electron donor. b) Zn(OH) 2 must be able to donate a proton. c) Zn(OH) 2 acts as a base in the presence of strong acid d) Zn(OH) 2 acts as an acid in the presence of strong base e) None of these statements are false 19. What is the hybridization of the central atom in BF 3? (3 points) a) sp b) sp 2 c) sp 3 d) sp 3 d e) sp 3 d 2
20. The polarity of covalent bonds derives from electronegativity differences. (1 point) 21. Given the following list of acids, which is/are strong? (5 points) 1) HClO 4 2) HClO 3 3) HNO 3 4) HI 5) HBr a) All are strong b) 1,3,4,5 c) 2,5 d) 1,3,4 e) None are strong 22. Calculate the normality of a solution that contains 156 g of calcium hydroxide, Ca(OH) 2 in 750 ml of solution. (3 points) a) 2.8 N b) 5.6 N c) 1.4 N d) 0.0056 N e) 0.0028 N 23. Is cis-dichloro-ethene (CH 2 Cl 2 ) polar or non-polar? (2 points) a) Polar b) Non-polar
24. Is H 3 O + polar or non-polar? (1 point) a) Polar b) Non-polar 25. In the following reaction, the oxidation state of Al changes from (3 points) 3KClO 4 + 8Al 3KCl + 4Al 2 O 3 a) 0 to +3 b) +3 to +1 c) 0 to +6 d) +3 to -2 e) +3 to 0 26. The following skeletal oxidation-reduction reaction occurs under acidic conditions. Write the balanced oxidation half-reaction. (5 points) Pb 2+ + Fe 3+ PbO 2 + Fe 2+ a) Fe 3+ Fe 2+ + e - b) Fe 3+ + e - Fe 2+ c) Pb 2+ + O 2 + 2e - PbO 2 d) Pb 2+ + 2H 2 O PbO 2 + 4H + + 2e - e) None of the above 27. A molecule with two double bonds and 4 single bonds has 6 sigma bonds. (1 point) 28. Water can be classified as (3 points) a) Neither an acid nor a base b) A strong acid and a weak base c) A weak acid and a weak base d) Only an acid e) A weak acid and a strong base
29. The conjugate acid of NH 3 is (2 points) a) NH 2 - b) NH 3 + c) NH 4 + d) NH 3 OH e) Not given 30. You wish to make a 0.264 M HClO 4 solution from a stock solution of 12.0 M HClO 4. How much concentrated acid must you add to obtain a total volume of 150 ml of the dilute solution? (5 points) a) 3.30 ml b) 6.60 ml c) 0.02 ml d) 0.04 ml e) 330.0 ml 31. What is the electronic geometry about the I in ICl 2 +? (3 points) a) linear b) trigonal planar c) trigonal bipyrimidal d) tetrahedral e) bent 32. What is the molecular geometry of the above molecule? (3 points) a) linear b) trigonal planar c) trigonal bipyrimidal d) tetrahedral e) bent