CHEMISTRY 101 EXAM 3 (FORM B) DR. SIMON NORTH

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1 1. Is H 3 O + polar or non-polar? (1 point) a) Polar b) Non-polar CHEMISTRY 101 EXAM 3 (FORM B) DR. SIMON NORTH 2. The bond strength is considerably greater in HF than in the other three hydrogen halides (HCl, HBr, and HI). (1 point) 3. Water can be classified as (3 points) a) A strong acid and a weak base b) A weak acid and a strong base c) A weak acid and a weak base d) Only an acid e) Neither an acid nor a base 4. When considering conjugate acids and bases, (2 points) a) Strong bases have strong conjugate acids. b) Strong acids have strong conjugate bases. c) Strong bases have weak conjugate acids. d) Weak acids have weak conjugate bases. e) None of the above is true. 5. 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

2 6. How many of the following statements are false? (5 points) a) 1 b) 2 c) 3 d) 4 e) 5 - Strong acids dissociate completely in water - 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). - Lewis acids and bases necessarily make water and salt when combined. 7. In the laboratory a student combines ml of a 1.0 M H 3 PO 4 with 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) 0.17 M b) 0.25 M c) 0.50 M d) 2.0 M e) 1.0 M 8. What are the approximate angles in ICl 2 -? (3 points) a) 90 b) 120 c) 109 d) 30 e) 180

3 9. According to Lewis Theory, an acid is any species that donates an electron pair. (1 point) 10. A molecule with 2 double bonds and 5 single bonds has 7 sigma bonds. (1 point) ml of N H 2 SO 4 solution required 50.5 ml of NaOH solution for neutralization. Calculate the normality and the molarity of the sodium hydroxide solution. (5 points) a) 0.11 M and N b) 0.22 M and 0.22 N c) 0.11 M and 0.11 N d) 0.11 M and N e) 0.44 M and 0.44 N 12. Given the following reaction, 2Na + H 2 O Na 2 O + H 2 which of the following statements is true? (5 points) a) Water is the oxidizing agent and Na is the reducing agent b) Na is the oxidizing agent and water is the reducing agent c) Water is being oxidized and Na is being reduced d) b) and c) are correct e) This is not a redox reaction 13. The polarity of covalent bonds derives from electronegativity differences. (1 point)

4 14. In the following reaction, the oxidation state of Al changes from (3 points) 3KClO 4 + 8Al 3KCl + 4Al 2 O 3 a) +3 to +1 b) +3 to -2 c) 0 to +3 d) +3 to 0 e) 0 to 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) Pb H 2 O PbO 2 + 4H + + 2e - c) Fe 3+ + e - Fe 2+ d) Pb 2+ + O 2 + 2e - PbO 2 e) None of the above 16. You wish to make a 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 300 ml of the dilute solution? (5 points) a) ml b) 6.60 ml c) 0.04 ml d) 0.02 ml e) 3.30 ml

5 17. What orbitals make up the pi bond between C and C in H 2 C=CH 2? (5 points) a) sp 2 on each C b) sp 3 on each C c) 2s on each C d) 2p on each C e) none of the above 18. Pi bonds can be formed between p orbitals. (1 point) 19. Is trans-dichloro-ethene (CH 2 Cl 2 ) polar or non-polar? (2 points) a) Polar b) Non-polar 20. The following unbalanced reaction takes place in acidic conditions. Cr 2 O 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) The conjugate acid of NH 3 is (2 points) a) NH 3 + b) NH 2 - c) NH 3 OH d) NH 4 + e) Not given

6 22. What is the normality of a solution prepared by dissolving 4.3 g of HClO 4 in 286 ml of water? (3 points) a) 0.60 N b) 0.30 N c) 0.15 N d) N e) N 23. What is the electronic geometry about the I in IBr 2 +? (3 points) a) linear b) trigonal planar c) tetrahedral d) trigonal bipyrimidal e) bent 24. What is the molecular geometry of the above molecule? (3 points) a) linear b) trigonal planar c) tetrahedral d) trigonal bipyrimidal e) bent 25. Given the following equation, (2 points) F - + BF 3 BF 4 - Which of the following statements is true? a) BF 3 is an Arrhenius acid and F - is an Arrhenius base b) BF 3 is a lewis base and F - is a lewis acid c) This is not an acid base reaction d) BF 3 is a lewis acid and F - is a lewis base e) Only Bronsted-Lowry theory can describe this reaction as an acid-base reaction

7 26. In the following reaction, (2 points) NH 3 + H 2 O NH F - Which is the Bronstead-Lowry base? a) H 2 O b) NH 3 c) neither 27. Given the following list of acids, which is/are strong? (5 points) 1) HBr 2) HClO 4 3) HClO 3 4) HNO 3 5) HI a) None are strong b) 1,2,4 c) 1,2,5 d) 1,2,3,4 e) All are strong 28. Calculate the normality of a solution that contains 156 g of calcium hydroxide, Ca(OH) 2 in 1500 ml of solution. (3 points) a) 2.8 N b) 5.6 N c) 1.4 N d) N e) N

8 29. H 2 CO 3 is a (2 point) a) strong acid b) weak acid c) strong base d) weak base e) soluble salt 30. 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) 31. The oxidation state of the carbon in the above question changes from (3 points) a) +3 to +4 b) +3 to 0 c) +4 to 0 d) no change in oxidation state e) none of the above 32. Given that Zn(OH) 2 is amphoteric, which of the following statements is false? (5 points) a) Zn(OH) 2 acts as an acid in the presence of strong base b) Zn(OH) 2 can react with an electron donor. c) Zn(OH) 2 must be able to donate a proton. d) Zn(OH) 2 acts as a base in the presence of strong acid e) None of these statements are false