Group Quizzes All group quizzes and answers for

Group Quizzes All group quizzes and answers for this semester! The numbers are off – deal with it.

Group Quiz 1 • Logging in to Mastering. Chemistry

Syllabus quiz: Group Quiz #2 • How many hour exams are there? How many get dropped? • What happens if you miss an exam? • How many points is the final exam worth? • How much is each homework assignment worth? • How many points is each group quiz worth and how many will count toward your final grade? • When are my office hours? • Name the author(s) of the textbook we are using this semester. • What sources of help are available to help you succeed in this course (list at least 3)?

Dimensional Analysis Practice • Problem 1. 17: Gemstones are weighed in carats, with 1 carat = 200 mg (exactly). What is the mass, in grams, of the Hope Diamond, the world’s largest blue diamond at 44. 4 carats? • The density of a steel ball bearing is 7. 81 g/cm 3. If the ball bearing is measured to have a volume of 1. 34 cm 3, what is its mass in milligrams?

Group Quiz #3 • Dimensional Analysis: One lap in an olympic swimming pool is 50 meters exactly. If an athlete swims 80 laps in one practice, how far did he/she swim (in miles)? • 1 inch = 2. 54 cm (exactly) • 12 inches = 1 foot (exactly) • 1 mile = 5280 feet (exactly)

Group Quiz #4: Subatomic Particles • Fill in the table below: # protons # neutrons 23 Na 21 Na 1+ 80 Br 1 - # electrons

Group Quiz #4 Answers • Fill in the table below: # protons # neutrons # electrons 23 Na 11 12 11 21 Na 1+ 11 10 10 80 Br 1 - 35 45 36

Group Quiz #5 • Calculate the energy of a photon that has a wavelength of 35. 6 nm (in the x-ray region). (Hint: Watch units!!!)

Group Quiz #5 Answer • Wavelength: 3. 56 x 10 -8 m • Frequency: 8. 43 x 1015 s-1 • Energy: 5. 58 x 10 -18 J

Group Quiz #6 • Write electron configurations for the following atoms/ions. • K (long-hand) • S 2 - (long-hand) • Mo (short-hand) • Al 3+ (long-hand) • Fe 2+ (short-hand) 10

Group Quiz #6 Answers • Write electron configurations for the following ions. • K (long-hand): 1 s 2 2 p 6 3 s 2 3 p 6 4 s 1 • S 2 - (long-hand): 1 s 2 2 p 6 3 s 2 3 p 6 • Mo (short-hand): [Kr] 5 s 1 4 d 5 • Al 3+ (long-hand): 1 s 2 2 p 6 • Fe 2+ (short-hand): [Ar] 4 s 0 3 d 6 11

Group Quiz #7 • For the periodic trend indicated, identify the larger atom or ion: • Radius: Cl or Cl-1 • Radius: O-2 or Na+1 • Ionization Eng: Na or K • Ionization Eng: Ca or Se • Electron Affinity: C or F 12

Group Quiz #7 Answers • • • Radius: Ionization Eng: Electron Affinity: Cl-1 O-2 Na Se F 13

Group Quiz #8 • Write names formulas and formulas for names: • • • Xe. F 6 ammonium sulfite Cr 3 N 2 K 3 PO 4 hydrochloric acid 14

Group Quiz #8 Answers • • • Name the following compounds: Xe. F 6: xenon hexafluoride ammonium sulfite: (NH 4)2 SO 3 Cr 3 N 2: chromium (II) nitride K 3 PO 4: potassium phosphate hydrochloric acid: HCl (aq) 15

Group Quiz #11 Sorry: No answers for these…. • Draw all possible Lewis Structures for: • • • POCl 3 BF 3 NO 2 PF 5 SO 3

Group Quizzes #12 and #13 • Determine the 1) molecular geometry/bond angles and 2) hybridization for each of the following molecules. Geometry/Bond Angles • • • Hybridization POCl 3 BF 3 NO 2 PCl 5 SO 3 17

Group Quiz #12 and #13 Answers • • • Tetrahedral, 109. 5 o, sp 3 Trigonal Planar, 120 o, sp 2 Bent, <120 o, sp 2 Trigonal Bipyramidal, 120 o and 90 o, sp 3 d Trigonal Planar, 120 o, sp 2 18

Group Quiz #14 • Which member of each pair has stronger intermolecular force (boiling point, heat of vaporization)? Explain your reasoning. CH 4 or CH 3 NH 3 or NF 3 CO 2 or SO 2 or O 3 I 2 or Cl 2 19

Group Quiz #14 Answers • Which member of each pair has stronger intermolecular force (boiling point, heat of vaporization)? Explain your reasoning. CH 3 larger NH 3 H-bridging SO 2 dipole-dipole O 3 dipole-dipole I 2 larger

Group Quiz #15 • Balance the following equations: • __Fe 2(SO 4)3 + __K 3 PO 4 __K 2 SO 4 + __Fe. PO 4 • __Hg(NO 3)2 + __ KI __Hg. I 2 + __ KNO 3 • __Li 2 O(s) + __ H 2 O __Li. OH • __HBr + __Ba(OH)2 __Ba. Br 2 + __H 2 O • __K 2 Pt. Cl 4 + __NH 3 __Pt(NH 3)2 Cl 2 + __KCl

Group Quiz #15 Answers • • • Fe 2(SO 4)3 + 2 K 3 PO 4 3 K 2 SO 4 + 2 Fe. PO 4 Hg(NO 3)2 + 2 KI Hg. I 2 + 2 KNO 3 Li 2 O(s) + H 2 O 2 Li. OH 2 HBr + Ba(OH)2 Ba. Br 2 + 2 H 2 O K 2 Pt. Cl 4 + 2 NH 3 Pt(NH 3)2 Cl 2 + 2 KCl

Group Quiz #16 • How many atoms are in 12. 987 g of iron? • How many H atoms are in a 3. 4215 gram sample of H 2 O?

Group Quiz #16 Answers • How many moles are in 12. 987 g of iron? • How many H atoms are in a 3. 4215 gram sample of H 2 O?

Group Quiz #17 • Determine the products of the reaction. Identify the phase of each compound, and balance the equation. Also write the ionic and net ionic equations. • Molecular: Na 2 S + Cr(NO 3)3 • Complete Ionic: • Net Ionic:

Group Quiz #17 Answers • Molecular: 3 Na 2 S(aq) + 2 Cr(NO 3)3(aq) Cr 2 S 3(s) + 6 Na. NO 3(aq) • Complete Ionic: 6 Na+(aq) + 3 S 2 -(aq) + 2 Cr 3+(aq) + 6 NO 3 -(aq) Cr 2 S 3(s) + 6 Na+(aq) + 6 NO 3 -(aq) • Net Ionic: 2 Cr 3+(aq) + 3 S 2 -(aq) Cr 2 S 3(s)

Group Quiz #15 • Identify the oxidation number of each element in the compounds or ions below: • Ba(Cl. O 3)2 • SO 32 -

Group Quiz #15 Answers • Ba: +2 • Cl: +5 • O: -2 • S: +4 • O: -2

Group Quiz #16 • Predict products of the following reactions. • Write correct phases for the products and balance each equation: • ___ Al (s) + ___ Na. NO 3 (aq) • ___ Na (s) + ___ O 2 (g) • ___ Na 2 SO 4 (aq) + ___ Pb(NO 3)2 (aq)

Group Quiz #16 Answers • Al (s) + Na. NO 3 (aq) No reaction • 4 Na (s) + O 2 (g) 2 Na 2 O (s) • Na 2 SO 4 (aq) + Pb(NO 3)2 (aq) 2 Na. NO 3 (aq) + Pb. SO 4 (s)

Group Quiz #17 • Complete the equation below (with phases) and balance it. • K 2 S(aq) + Ag. NO 3(g) • If you combine 10. 21 m. L of 0. 152 M K 2 S with 1. 0092 g Ag. NO 3, how much solid product can be formed? • If 0. 5744 g of product were actually formed, what is the percent yield?

Group Quiz #17 Answers • Complete the equation below (with phases) and balance it. – K 2 S(aq) + 2 Ag. NO 3(aq) Ag 2 S(s) + 2 KNO 3(aq) • If 0. 5744 g of product were actually formed, what is the percent yield?

Group Quiz #19 • What is the concentration of sodium hydroxide if it took 23. 48 m. L of base to neutralize 15. 39 m. L of 1. 20 M phosporic acid?

Group Quiz #19 Answer

Group Quiz #18 • What mass of sodium acetate must be used to make 100. 0 m. L of a 0. 100 M solution? • What is the concentration of this solution if you then add 400. 0 m. L of water to it?

Group Quiz #18 Answers • What mass of sodium acetate must be used to make 100. 0 m. L of a 0. 100 M solution? • What is the concentration of this solution if you then add another 400. 0 m. L of water to it?

Group Quiz #19 Sorry: No answers…. • What mass of sodium azide (Na. N 3) is needed to generate 75. 2 L of nitrogen gas (and solid sodium) at 100. 0 o. C and 1. 00 atm? • (Hint: Start with a balanced chemical equation!)

Group Quiz #21 • A hot piece of copper (at 98. 7 o. C, specific heat = 0. 385 J/g • o. C) weighs 34. 6486 g. When placed in room temperature water, it is calculated that 915. 1 J of heat are released by the metal. • What gains heat? What loses heat? What is the final temperature of the metal? • Watch signs!!!!

Group Quiz #21 Answer • -951. 1 J = (34. 6486 g)(0. 385 J/g • o. C)(x – 98. 7 o. C) • -68. 5997 o. C = x – 98. 7 o. C • x = 30. 1 o. C

Group Quiz #22 I didn’t give this one but would have if there had been time…. • Given the following equations: • 2 CO 2 (g) + 2 CO (g) 566. 0 k. J • ½ N 2 (g) + ½ O 2 (g) NO (g) k. J DH = 90. 3 • Calculate the enthalpy change for: • 2 CO (g) + 2 NO (g) 2 CO 2 (g) + N 2 (g) DH = ? 40

Group Quiz #22 Answers • 1: Reverse • O 2 (g) + 2 CO (g) 2 CO 2 (g) DH = -566. 0 k. J • 2: Reverse, x 2 • 2 NO (g) N 2 (g) + O 2 (g) DH = -180. 6 k. J • 2 CO (g) + 2 NO (g) 2 CO 2 (g) + N 2 (g) =DH = -746. 6 k. J

Group Quiz #22 – Given in class • Use Standard Heat of Formation values to calculate the enthalpy of reaction for: • C 6 H 12 O 6(s) C 2 H 5 OH(l) + CO 2(g) • Hint: Is the equation balanced? DHof (C 6 H 12 O 6(s)) = -1260. 0 k. J/mol DHof (C 2 H 5 OH(l)) = -277. 7 k. J/mol DHof (CO 2(g)) = -393. 5 k. J/mol

Group Quiz #22 Answer • C 6 H 12 O 6(s) 2 C 2 H 5 OH(l) + 2 CO 2(g) • DHof (C 6 H 12 O 6(s)) = -1260. 0 k. J/mol • DHof (C 2 H 5 OH(l)) = -277. 7 k. J/mol • DHof (CO 2(g)) = -393. 5 k. J/mol • DHorxn = [2 mol (-277. 7 k. J/mol) + 2 mol (-393. 5 k. J/mol)] – [1 mol (-1260. 0 k. J/mol)] = -82. 4 k. J