Chemistry 400: General Chemistry Miller Fall 2015 Final Exam Part Deux December 14, 2015 Approximately 150 points

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Chemistry 400: General Chemistry Name: Miller Fall 2015 Final Exam Part Deux December 14, 2015 Approximately 150 points Please answer each of the following questions to the best of your ability.

1 Chemistry 400: General Chemistry Name: Miller Fall 2015 Final Exam Part Deux December 14, 2015 Approximately 150 points Please answer each of the following questions to the best of your ability. If you wish to receive partial credit, please show your work. For all ionic species, please show the charge on each ion to receive full credit. Good luck! All Lewis Structures must include all valence electrons. Element Electronegativity F 4.0 O 3.5 Cl 3.0 N 3.0 S 2.8 Br 2.8 C 2.5 H 2.1 I. Nomenclature (4 points each, spelling counts) If the name is given, please give the formula. If the formula is given, please give the name. A. NaNO 2 B. CH 3 COOH C. Fe 2 S 3 D. N 2 O 3 E. CuSO 4 5H 2 O II. Drawing 1. For CF 4 : (i) Draw the correct Lewis structure. (4 points) (ii) Draw the correct electron geometry and (iii) Draw dipoles. (6 points) (iv) What is the bond angle around the oxygen atom? Use a <, >, or = symbol as part of your answer. (2 points) (v) Is this molecule polar or nonpolar? (4 points) 1

2 2. If MgSO4 xh 2 O, is heated to 250 C, all the waters of hydration evaporate. On heating a g sample of the hydrate MgSO4 xh 2 O, g of MgSO 4 remains. How many molecules of water occur per formula unit of MgSO 4? In other words, solve for x. For this problem, your show your work if you'd like to receive any credit. (10 points) 3. Will the ph of M HCl or M CH 3 COOH be lower? Explain your choice with specific reference to the types of acids involved and their percents of ionization. (8 points) 2

3 4. There is a relationship between intermolecular forces, temperature, and the temperatures at which the solid, liquid, and gas phases exist. Each blank will be filled in with one of the words in bold. You may use each word more than once. (1 point per blank) A. is proportional to the average kinetic energy. B. At low temperatures, materials are in the phase. In this phase, are strong enough to keep the particles in the material (atoms, ions, or molecules) close enough such that the particles have 3- dimensional order. C. At high temperatures, materials are in the phase. In this phase, no matter how strong the are, the energy supplied by the high temperatures is enough to overcome the. D. At intermediate temperatures, materials are in the phase. The exact temperatures of the phase transitions depend upon the strength of. 3

4 5. Calculate the change in the enthalpy of reaction, ΔH rxn, for the following combustion reaction two ways: C 2 H 6 (g) O 2 (g) 2 CO 2 (g) + 3 H 2 O(g) A. Using bond dissociation energies. (14 points) B. Using standard changes in the enthalpy of formation, ΔH f. (6 points) ΔH f (C 2 H 6 ) = -84 kj/mol 4

5 6. In the experiment below, the electron shooter shoots one electron at a time through the double slits at the screen. Draw the pattern that the electrons make on the screen after a long period of time in which many electrons have been shot at the screen but the electrons have been shot at the screen one at a time. A. No laser (no observer) to determine which slit the electron goes through (4 points) electron shooter: shoots one electron at a time double slit screen B. A laser (an observer) is present to determine which slit the electron goes through (4 points) electron shooter: shoots one electron at a time double slit screen 7. Define an orbital. Make sure to use the words volume and probability in your definition (6 points) 5

6 8. Write a paragraph about the relationship between the 3d and 4s orbitals in terms of energy. For what elements is 3d lower in energy? For what elements is 4s lower in energy? To answer this question, use the electron configurations (with or without noble gas configurations) of a potassium atom, a potassium ion, a titanium atom, and a doubly charged titanium ion. (12 points) electron configurations: K atom K + ion Ti atom Ti 2+ ion 6

7 9. A. Draw the best Lewis Structure for NH 3 and the best Lewis structure for ClH 3, named chlorine trihydride. All atoms will have zero formal charge. For each Lewis structure, calculate the difference in electronegativity for each type of bond and draw dipoles for each bond (if they exist). (8 points) B. Determine the dominant type of intermolecular force for each molecules above and suggest a reason why they are different (even though the differences in electronegativity of each type of bond might suggest otherwise). (8 points) 10. The nonvolatile, nonelectrolyte aspirin, C 9 H 8 O 4, is soluble in diethyl ether CH 3 CH 2 OCH 2 CH 3. How many grams of aspirin are needed to generate an osmotic pressure of 7.72 atm when dissolved in 190 ml of a diethyl ether solution at 298 K. (8 points) 7

8 11. Shown below is the distribution of velocities for hydrogen (H) atoms at 300 K. Place a line on this graph that approximately represents the distribution of velocities for helium (He) atoms at 300 K. (4 points) Fraction of Atoms x 10^ Velocity (m/s) 8

9 12. From calculations in class, it was clear that the wavelength of an electron was approximately the same size as an atom of hydrogen, r = 0.05 nm. A. Calculate the wavelength of an electron traveling at 2.2 x 10 6 m/s. (6 points) B. Are there any other particles or atoms for which the wavelength is comparable to the size of the atom? If so, please show through calculations. If not, then please explain why. (10 points) 9

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11 Chemistry 400 Conversions and Equations 1 L = qt 1 m = in 1 gal = 4 qt 1 qt = 4 cups 1 mile = 5280 feet g = 1 lb 1 yd = 36 in = 3 ft 1 lb = 16 oz 1 atm = kpa = bar = 14.7 psi ºF = 1.8 º C + 32 N a = 6.02 x calorie = J For gases: standard T = K, P = 1 atm q = Energy = (mass) (C sp ) (ΔT) specific heat of water = J/g C average atomic mass = (mass isotope 1)(%) + (mass isotope 2)(%) + (mass isotope 3)(%) 100% P O2 = (% O 2 ) P T P 1 V 1 / T 1 = P 2 V 2 / T 2 P T = P 1 + P 2 + P 3 + PV=nRT w = -P ΔV λ = c ν $ E = J Z n 1 ' & 2 ) % 2 n 1 ( E = hν λ = h mv KE = ½ mv2 ΔxmΔv = h 4π Mass of electron = kg h = J s K w = [H 3 O + ] [OH ] = [H + ] [OH ] = c = m/s C 1 V 1 = C 2 V 2 % yield = actual/theoretical 100% 1 L atm = J R= L atm/mol K = J/mol K Specific heat of ice: 2.09 J/g C Specific heat of water: J/g C Specific heat of steam: 2.03 J/g C Heat of fusion of H 2 O = ΔH fus = 6.02 kj/mol Heat of vaporization of H 2 O = ΔH vap = 40.7 kj/mol " ΔT = m i K π = i M R T ln P % 2 $ ' = ΔH " vap 1 1 % $ # P 1 & R # T 2 T 1 & ' 1 ppm = 1 x 10-6 g/ml 1 ppb = 1 x 10-9 g/ml 1

Chemistry 400 Conversions and Equations Average Single Bond Dissociation Energy (in kj/mol) H C N O F Si P S Cl Br I 436 414 389 464 565 323 322 368 431 364 297 H 347 305 360 485 301 272 339 276 213

12 Chemistry 400 Conversions and Equations Average Single Bond Dissociation Energy (in kj/mol) H C N O F Si P S Cl Br I H C N O F Si P S Cl Br 151 I Comparison of Average Single, Double and Triple Bond Energies (in kj/mol) Bond Type Single Bond Double Bond Triple Bond C C N N O O C N C O * 1072 C Cl *For CO 2, the C=O bond is 799 kj/mol Boiling Point Elevation and Freezing Point Depression Constants Solvent Formula K b ( C/m) K f ( C/m) Water H 2 O Ethanol CH 3 CH 2 OH Chloroform CHCl Benzene C 6 H Diethyl ether CH 3 CH 2 OCH 2 CH Element Electronegativity F 4.0 O 3.5 Cl 3.0 N 3.0 S 2.8 Br 2.8 C 2.5 H 2.1 2

13 Chemistry 400 Conversions and Equations Material ΔH f (kj/mol) Material ΔH f (kj/mol) Ag(s) 0 H 2 O 2 (l) Ag + (aq) H 3 O + (aq) Al(s) 0 HBr(g) 36.3 Al 3+ (aq) HCl(aq) Al 2 O 3 (s) HCl(g) 92.3 AlCl 3 (aq) H 2 SO 4 (l) 814 AlCl 3 (s) I 2 (g) Br(g) I 2 (s) 0 Br 2 (g) 30.9 Mg 2+ (aq) Br 2 (l) 0 MgCl 2 (aq) C(g) N(g) C(s, dia) 1.88 N 2 (g) 0 C(s, gr) 0 N 2 H 4 (l) 50.6 C 2 H 4 (g) 52.4 N 2 O(g) 81.6 C 2 H 4 O(g) N 2 O 4 (g) 11.1 C 2 H 5 OH(l) Na(s) 0 C 6 H 12 O 6 (s) Na + (aq) C 3 H 8 (g) Na 2 SO 4 (s) CH 3 CH 2 CH 2 CH 3 (l) NaCl(aq) Ca(g) NaCl(s) Ca(OH) 2 (aq) 1003 NaOH(aq) Ca(OH) 2 (s) NH 3 (aq) Ca(s) 0 NH 3 (g) 45.9 Ca 2+ (aq) NH + 4 (aq) Ca 2+ (g) NH 4 Cl(aq) CaCl 2 (s) NH 4 Cl(s) CaCO 3 (s) NH 4 NO 3 (aq) CaF 2 (s) NH 4 NO 3 (s) CaO(s) NI 3 (s) 192 CH 3 OH(g) NO(g) 91.3 CH 4 (g) 74.6 NO 2 (g) 33.2 CHCl 3 (l) 134 O(g) Cl (aq) O 2 (g) 0 Cl(g) O 3 (g) Cl 2 (g) 0 OH (aq) CO(g) SO 2 Cl 2 (g) 364 CO 2 (g) SO 2 (g) Cu(s) 0 SO 2 4 (aq) Cu 2+ (aq) 64.9 Zn(s) 0 Fe 2 O 3 (s) 824 Zn 2+ (aq) Fe 3 O 4 (s) HgO(s) 90.8 H(g) 218 Hg(l) 0 H + (aq) 0 H 2 (g) 0 H 2 O(g) H 2 O(l) H 2 O(s) H 2 O 2 (aq)

14 Chemistry 400 Conversions and Equations Unit of Concentration Symbol Formula Mass/mass percent % (w/w) %(m/m) = grams of solute x 100 grams of solution Mass/volume percent % (w/v) % (m/v) = grams of solute x 100 ml of solution Volume/volume percent % (v/v) % (v/v) = ml of solute x 100 ml of solution Molarity M M = moles of solute L of solution parts per million ppm ppm = grams of solute x 10 6 grams of solution 4

Chemistry 400: General Chemistry Miller Exam II November 4, 2015 Approximately 150 points

Chemistry 400: General Chemistry Name: Miller Exam II November 4, 2015 Approximately 150 points Please answer each of the following questions to the best of your ability. If you wish to receive partial