Sample Exam 2

Name:________KEY__________ Sample Exam 2 – Chapters 4, 5, 7 Show ALL work for FULL credit!! 1. How many valence electrons are there in the molecule disilicon hexahydride, Si2H6? a. 8 b. 14 c. 18 d. 20 2. What is the correct electron domain geometry for nitrite ion, NO2-? a. linear b. bent c. tetrahedral 3. What is the correct molecular shape for ClF3? a. tetrahedral b. trigonal bipyramidal d. trigonal planar c. T-shaped d. square pyramidal 4. What is the correct bond angle for a molecule that is tetrahedral in electron domain geometry and bent in molecular shape? a. <180° b. <90° c. <120° d. <109.5° 5. A triple bond consists of the following: a. 3 σ bonds b. 2 σ and 1 π bonds c. 1 σ and 1 π bond 6. Predict the molecular shape for the molecule SF4. a. square pyramidal b. trigonal planar c. see-saw d. 1 σ and 2 π bonds d. tetrahedral - 7. What is the overall polarity for nitrite ion, NO2 ? a. polar b. nonpolar - 8. How many resonance structures are possible for nitrite ion, NO2 ? a. 1 b. 2 c. 3 d. 4 9. What is the hybridization for the central atom in the molecule ClF3? a. sp2 b. sp3 c. sp3d d. sp3d2 10. What is the molecular geometry (shape) for a molecule that has two lone pairs and four bonded atoms around the central atom? a. bent b. trigonal bipyramidal c. square planar d. see-saw 11. What is the formal charge on the carbon atom in cyanide ion, CN-1? a. 0 b. +1 c. -1 d. -2 12. What is the correct Roman Numeral used for tin in Sn(SO4)2? a. I b. II c. III d. IV 13. What does the Greek prefix hepta- represent? a. 4 b. 5 c. 6 d. 7 14. If 0.25 moles of H2 reacts with excess N2, how many moles of NH3 are produced in the combination reaction 3 H2(g) + N2(g) → 2 NH3(g)? a. 0.25 mol b. 0.50 mol c. 0.38 mol d. 0.17 mol 15. What is the precipitate in the following reaction: KCl (aq) + Pb(NO3)2 (aq) → a. KCl b. KNO3 c. PbK d. PbCl2 16. What is the oxidizing agent in the reaction N2(g) + 3 H2(g) → 2 NH3(g) a. H in NH3 (g) b. N in NH3 (g) c. H2 (g) d. N2 (g) 17. What products are produced when LiHCO3 (s) undergoes decomposition? a. Li2O (s) and CO2 (g) b. LiOH (s) and CO2 (g) c. LiH (aq) and CO2 (g) d. Li2CO3 (s), CO2 (g), and H2O (g) 18. Classify the following reaction: CaO(s) + CO2(g) → CaCO3(s) a. combination b. combustion c. neutralization d. decomposition 19. What is the oxidation number for sulfur in the compound K2SO4? a. +3 b. +6 c. +7 d. +4 20. Which one of the following metals will react with Sn(NO3)2(aq)? a. Cu(s) b. Ni(s) c. Sn(s) d. Pb(s) 21. Classify the following reaction: 2 NaOH(aq) + Sr(s) → 2 Na(s) + Sr(OH)2(aq) a. combination b. combustion c. neutralization d. single replacement 22. If a student ran a chemical reaction calculated the theoretical yield to be 3.78 g. If the percent yield is 76.4%, what mass did the student actually obtain? a. 2.89 g b. 4.95 g c. 20.2 g d. 0.202 g 23. Which one of the following solutions will react Ag(s)? a. Al(NO3)3(aq) b. HNO3(aq) c. Cu(NO3)2(aq) d. Au(NO3)3 24. What is the net ionic equation for the reaction of Na2SO4 (aq) and AgNO3 (aq)? b. Ag+ (aq) + NO3- (aq) → AgNO3 (s) c. 2 Na+ (aq) + SO42- (aq) → Na2SO4 (s) d. Na+ (aq) + NO3- (aq) → NaNO3 (s) e. 2 Ag+ (aq) + SO42- (aq) → Ag2SO4 (s) 25. Calculate the moles available to react when a graduated cylinder contains 25.0 mL of 2.50 M H2SO4. a. 0.0625 mol b. 62.5 mol c. 100. mol d. 0.0100 mol 26. Which of the following is considered a weak acid? a. HCl (aq) b. HI (aq) c. HBr (aq) d. HF (aq) 27. What volume of a 9.00 M KCl solution is required to make 45.0 mL of a 2.50 M KCl solution? a. 162 mL b. 1010 mL c. 0.500 mL d. 12.5 mL 28. What is the coefficient for oxygen in the reaction: 2 C8H18(g) + 25 O2(g) → 16 CO2(g) + 18 H2O(g) ? a. 25 b. 2 c. 16 d. 18 29. Draw the correct Lewis Structure for ALL of the following molecules and answer the questions: PI3 ICl4- # valence electrons: 26 Hybridization: sp3 EDG:tetrahedral Shape: trigonal pyramidal TeF4 Polar? Y/N Shape: square planar XeBr2 Hybridization: sp3d Shape: see-saw Hybridization: sp3d2 EDG:octahedral # valence electrons: 34 EDG:trigonal bipyramidal # valence electrons: 36 Polar? Y/N Polar? Y/N # valence electrons: 22 EDG: trigonal bipyramidal Shape: linear 30. Please name the following compounds (spelling counts!): a. KIO2 potassium iodite b. Co3N2 cobalt(II) nitride c. K3PO4 potassium phosphate d. TiS titanium(II) sulfide e. P4S6 tetraphosphorus hexasulfide f. IF3 iodine trifluoride g. SrCO3 strontium carbonate 31. Please write the correct formula for the following compounds: a. aluminum hydroxide Al(OH)3 b. dinitrogen nonoxide N2 O9 c. vanadium(IV) oxide VO2 d. silver nitrate AgNO3 e. sodium sulfite heptahydrate Na2SO3•7H2O f. calcium fluoride CaF2 g. sodium perchlorate NaClO4 Hybridization: sp3d Polar? Y/N 32. Answer the following questions regarding the structure for Retinol below: How many sigma, σ, bonds are there? __51__ How many pi, π, bonds are there? ___5_____ 33. Draw three resonance structures for the molecule OCS (in that order) and evaluate each using formal charges. 0 0 0 Best Each element has a zero formal charge +1 0 -1 -1 0 +1 Worst The more EN atom (oxygen) has a positive F.C. 34. Write a balanced reaction for the decomposition of solid manganese (II) chloride, MnCl2 (s). Δ MnCl2(s) → Mn(s) + Cl2(g) 35. Calculate the molarity of a calcium nitrate solution made by dissolving 100.0 g of Ca(NO3)2 in enough water to fill a volumetric flask to the 5.00 L mark. 100.0 g Ca(NO3)2 1 mole Ca(NO3)2 = 0.6094 moles Ca(NO3)2 164.088 g M = 0.6094 mol Ca(NO3)2 5.00 L M = 0.122 M Ca(NO3)2 36. Write the molecular equation, total ionic equation, and net ionic equation for the reaction of aqueous H2SO4 with aqueous KOH. a. Molecular Equation: ____H2SO4 (aq) + _2__KOH (aq) → 2 H2O(l) + K2SO4(aq) b. Total Ionic Equation: 2H+(aq) + SO42-(aq) + 2K+(aq) + 2OH-(aq) → 2H2O(l) + 2K+(aq) + SO42-(aq) c. Net Ionic Equation: 2H+(aq) + 2OH-(aq) → 2H2O(l) 37. A student performed a titration of 29.5 mL of 1.33 M H2SO4 with 16.8 mL of NaOH. What is the molarity of the NaOH? ____H2SO4 (aq) + __2__NaOH (aq) → __2__ H2O (l) + ____ Na2SO4 (aq) 0.0295 L H2SO4(1.33 mol H2SO4)( 2 mol NaOH) = 0.07847 mol NaOH ( 1 L H2SO4 )(1 mol H2SO4 ) M = 0.07847 mol NaOH = 4.67 M NaOH 0.0168 L 38. Classify each of the following as a nonelectrolyte, a weak electrolyte, or a strong electrolyte: a. Al2(SO4)3 nonelectrolyte weak electrolyte strong electrolyte b. K2CrO4 nonelectrolyte weak electrolyte strong electrolyte c. C6H12O6 nonelectrolyte weak electrolyte strong electrolyte d. Fe(OH)3 nonelectrolyte weak electrolyte strong electrolyte 39. Show the beaker drawings for the following compounds once they are placed in water: H+ NO3CaSO4 HNO3 CaSO4 40. What mass of Al2O3 (s) is produced when 18.53 grams of solid Al is combined with 10.22 L of O2 gas at STP? Δ __3__ O2 (g) + __4__ Al (s) → __2__ Al2O3 (s) 18.53 g Al ( 1mol Al )( 2 mol Al2O3) (101.96 g Al2O3 )= 35.0 g Al2O3 (26.98 g Al )(4 mol Al )( 1 mol Al2O3 ) 10.22 L O2 ( 1mol O2 )( 2 mol Al2O3) (101.96 g Al2O3 )= 31.0 g Al2O3 (22.41 L O2)( 3 mol O2 )( 1 mol Al2O3 ) 41. Identify the type of reaction and predict products for the following reactions. Be sure to balance the final equation and write in the correct physical states. If no reaction occurs write NR. a. combustion Type _6__C6H6(l) + _6_O2(g) → 6 CO2(g) + H2O(g) b. No Rxn Type c. decomposition Type ____Fe2O3(s) → 4 Fe(s) + 3 O2(g) d. neutralization Type _2_HBr(aq) + ____Ba(OH)2(aq) → H2O(l) + BaBr2(aq) e. single repalcementType _2__Ni(NO3)3(aq) + _3__Zn(s) → 3 Zn(NO3)2(aq) + 2 Ni(s) ____Ag(s) + ____AlCl3(aq) → No Products