1. How many grams of Cr can be produced by the reaction of 44.1 g of Cr 2 O 3 with 35.0 g of Al according to the following chemical reaction?

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1 Final Exam Revision 1. How many grams of Cr can be produced by the reaction of 44.1 g of Cr 2 O 3 with 35.0 g of Al according to the following chemical reaction? 2Al + Cr 2 O 3 Al 2 O 3 + 2Cr Ans: 30.2 g 2. Oxidation of a hydrocarbon gave a product composed of carbon, hydrogen, and oxygen. The product that was purified and sent off for elemental analysis giving the following mass percents: 68.85% C and 4.95% H. Determine the empirical formula of this compound. Ans: C 7 H 6 O 2 3. A sample of hydrogen gas was collected over water at 21 C and 685 mmhg. The volume of the container was 7.80 L. Calculate the mass of H 2 (g) collected. (Vapor pressure of water = 18.6 mmhg at 21 C.) Ans: g 4. A g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/ C. If the temperature rise of the calorimeter with water was C, calculate the enthalpy of combustion of magnesium. Mg(s) + 1/2O 2 (g) MgO(s) Ans: 602 kj/mol 5. A ground-state chromium atom has how many unpaired electrons? Ans: 6 6. Write the electron configuration for the aluminum ion. Ans: 1s 2 2s 2 2p 6 7. Write the electron configuration of the iron(iii) ion. Ans: [Ar]3d 5 8. Which of the following ground-state ions has the largest number of unpaired electrons? A) Cr 2+ B) Mn 2+ C) Ni 2+ D) Cu + E) Co 2+ 1

2 9. Write the second ionization energy of nitrogen. Ans: N + (g) N 2+ (g) + e 10. Write the third ionization energy of vanadium. Ans: V 2+ (g) V 3+ (g) + e 11. Which of the elements listed below has the highest first ionization energy? A) He B) Ne C) Ar D) Kr E) Xe 13. Which one of the following ionic solids would have the largest lattice energy? A) NaCl B) NaF C) CaBr 2 D) CsI E) CaCl Calculate the lattice energy of LiCl (s), given the following data: H(sublimation) Li = kj/mol I 1 (Li) = 520 kj/mol Bond energy (Cl Cl) = kj/mol EA (Cl) = 349 kj/mol H o f for LiCl(s) = -380 kj/mol Ans: 828 kj/mol 13. A polar covalent bond would form in which one of the following pairs of atoms? A) Cl - Cl B) Si - Si C) Ca - Cl D) Cr - Br E) P - Cl 14. Which one of these polar covalent bonds would have the greatest percent ionic character? A) H - Br B) H - Cl C) H - F D) H - I 15. The bond in which one of the following pairs of atoms would be the most polar? A) B - C B) C - N C) C - O D) Si - O E) C - C 16. The number of lone electron pairs in the NO 2 ion is. Ans: The Lewis structure for CS 2 is: Ans: S C S 18. The number of resonance structures for the nitrate ion that satisfy the octet rule is Ans: 3 2

3 19. What is the formal charge on the oxygen atom in N 2 O (the atomic order is N N O)? Ans: What is the formal charge on sulfur in the best Lewis structure for the SCN (thiocyanate) ion? Ans: Estimate the enthalpy change for the reaction 2CO + O 2 2CO 2 given the following bond energies. BE(C-O) = 1074 kj/mol BE(O=O) = 499 kj/mol BE(C=O) = 802 kj/mol Ans: 561 kj/mol 22. Give the number of lone pairs around the central atom and the molecular geometry of SCl 2. Ans: 2 lone pairs, bent 23. Give the number of lone pairs around the central atom and the molecular geometry of SeF 4. Ans: 1 lone pair, distorted tetrahedron (seesaw) 24. Give the number of lone pairs around the central atom and the molecular geometry of IF 5. Ans: 1 lone pair, square pyramidal 25. Give the number of lone pairs around the central atom and the geometry of the ion PCl 4. Ans: 1 lone pair, distorted tetrahedron (seesaw) 26. According to VSEPR theory, the geometry of the PH 3 molecule is Ans: trigonal pyramidal 27. The bond angle in ICl 2 is expected to be Ans: The bond angles in CO 3 2 are expected to be Ans:

4 29. Which one of the following molecules is nonpolar? A) NH 3 B) OF 2 C) CH 3 Cl D) H 2 O E) BeCl Which one of the following molecules has a non-zero dipole moment? A) BeCl 2 B) Br 2 C) BF 3 D) IBr E) CO Which one of the following molecules has a zero dipole moment? A) CO B) CH 2 Cl 2 C) SO 3 D) SO 2 E) NH Indicate the type of hybrid orbitals used by the central atom in PCl 3. Ans: sp Indicate the type of hybrid orbitals used by the central atom in SF 6. Ans: sp 3 d What is the hybridization of the As atom in the AsF 5 molecule? Ans: sp 3 d 35. The number of pi bonds in the molecule below is Ans: The net ionic equation for the reaction is H 2 O 2 + I +H + I 2 + H 2 O [unbalanced] (a) How many moles of I - were required for the titration if ml of a M KI solution was needed to reach the end point? Ans: x 10-3 mol I - (b) How many gram of H 2 O 2 is needed for this titration? Ans: g 37. Calculate the standard cell emf for the following cell: Mg Mg 2+ NO 3 (acid soln) NO(g) Pt Ans: 3.33 V 4

5 38. A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl 3 electrolyte. Calculate the number of moles of gold deposited in 3.0 min by a constant current of 10. A. Ans: 6.2 x 10 3 mol 39. How many coulombs (C) of electrical charge must pass through an electrolytic cell to reduce 0.44 mol Ca 2+ ion to calcium metal? Ans: 85,000 C 40. What current is needed to deposit g of chromium metal from a solution of Cr 3+ in a period of 1.00 hr? Ans: A 41. A 15 kg of Al bar is attached to an iron tank and the current flow is 0.5 A between the Al and the iron tank. How many years for the Al to be consumed? Ans: 10.2 years 42. The same quantity of charge flows through two electrolysis cells. In the first cell, 5.30 g of Cu are deposited from a solution containing Cu 2+ and 2.03 g of an unknown metal (M) from a solution containing M 2+ ions in the second cell, (a) Calculate the molar mass of the unknown metal. Ans: g/mol (b) What is the unknown metal? Ans: Magnesium 43. Which of these is the systematic name for the compound represented below? Ans: 3-methyl-1-pentene 44. Name the following compound. Ans: 1,3-dichlorocyclobutane 5

6 45. Write the functional group of (a) alcohol (b) carboxylic acids (c) ketones (d) ester (e) aldehyde. O O O Ans: (a) R O H (b) R C OOH (c) R C R (d) R C OR O (e) R C H 46. The name for the compound with the formula CH 3 CH 2 CH 2 CH 2 OH is Ans: butanol 47. Which type of organic compound does not contain a carbonyl group? A) ethers B) carboxylic acids C) ketones D) aldehydes E) esters 48. Which of the following compounds are isomers of each other? I. pentane II. 2-methylbutane III. 2,3-dimethylbutane IV. 2,2-dimethylpropane V. 1-hexene Ans: I, II, and IV 49. Name the following compound: Ans: 2,2-dimethylbutane 50. Draw and name the structural formulas of all the isomers of dimethyl benzene. Ans: 1,2-dimethylbenzene 1,3-dimethylbenzene 1,4-dimethylbenzene (ortho-dimethylbenzene) (meta-dimethylbenzene) (para-dimethylbenzene) 6