CHEM133 Week 16 Final Exam

1. Question: Which one of the following is most likely to be an ionic compound? 2. Question: The phosphorus atom in PCl3 would be expected to have a 3. Question: How many covalent bonds will be drawn to phosphorous in PO43– for the dot structure that expands the octet to minimize formal charge and if necessary places negative formal charges on the most electronegative atom(s) 4. Question: Calculate the lattice energy of NaBr(s), given the following thermochemical equations, where ΔIE and ΔEA are ionization energy and electron affinity, respectively. 5. Question: Which of the following groups contains no ionic compounds? 6. Question: Which of the elements listed below is most likely to exhibit an expanded octet in its compounds? 7. Question: Which of the following substances will display an incomplete octet in its Lewis structure? 8. Question: How many lone pairs of electrons are on the Xe atom in XeF6? 9. Question: When comparing Be2 and H2: 10. Question: Which molecule contains a triple bond? 11. Question: X-rays from a copper X-ray tube, at l = 1.54062 Å, are diffracted at an angle of 11.30o from a sample of metallic platinum. Assuming that n = 1, what is the distance between the planes that gives rise to this reflection? 12. Question: Vanadium crystallizes in a body-centered cubic lattice, and the length of the edge of a unit cell is 305 pm. What is the density of V? 13. Question: If you wanted to synthesize a compound that had a fairly low melting point and a low density, you would want to synthesize: 14. Question: What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 175 pm? 15. Question: The radius of an indium atom is 0.163 nm. If indium crystallizes in a face-centered unit cell, what is the length of an edge of the unit cell? 16. Question: A 3.9 g sample of Colorado oil shale is burned in a bomb calorimeter, which causes the temperature of the calorimeter to increase by 5.0°C. The calorimeter contains 1.00 kg of water (heat capacity of H2O = 4.184 J/g°C) and the heat capacity of the empty calorimeter is 0.10 kJ/°C. How much heat is released per gram of oil shale when it is burned? 17. Question: Which of the following has a ΔH°f = 0 kJ/mol? 18. Question: The heat of vaporization of water at 100°C is 40.66 kJ/mol. Calculate the quantity of heat that is absorbed/released when 5.00 g of steam condenses to liquid water at 100°C. 19. Question: What is the specific heat capacity of a metal if it requires 178.6 J to change the temperature of 15.0 g of the metal from 25.00°C to 32.50°C? 20. Question: You take 243.8 g of a solid at 30.0°C and let it melt in 425 g of water. The water temperature decreases from 85.1°C to 30.0°C. Calculate the heat of fusion of this solid. 21. Question: If the pressure of a gas sample is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sample change? 22. Question: A physics experiment is conducted at a pressure of 14.0 kPa. What is this pressure in mmHg? 23. Question: At constant temperature, the volume of the container that a sample of nitrogen gas is in is doubled. As a result, the pressure of the nitrogen gas is halved. The amount of nitrogen gas is unchanged in this process. This is an example of: 24. Question: When 0.72 g of a liquid is vaporized at 110°C and 0.967 atm, the gas occupies a volume of 0.559 L. The empirical formula of the gas is CH2. What is the molecular formula of the gas? 25. Question: At constant temperature and volume, a sample of oxygen gas is added to a sample of nitrogen gas. The pressure of the mixture is found by adding the pressures of the two individual gases. This is an example of: 26. Question: For the electronic transition from n = 3 to n = 5 in the hydrogen atom. 27. Question: For the electronic transition from n = 2 to n = 4 in the hydrogen atom. 28. Question: Draw all the resonance structures of the nitrate ion, NO3 29. Question: Consider the following molecules, H2, He2, and O2…. a) Which one has a bond order of 2? ___________, b) Which one has a single bond? ___________, c) Which is the most unstable? ___________, d) Write them in order of increasing stability. 30. Question: Solid KF has a lattice energy of 804 kJ/mol and a heat of solution (in water) of -15 kJ/mol. RbF has a lattice energy of 768 kJ/mol and a heat of solution (in water) of -24 kJ/mol. Which salt forms stronger attractions with water? 31. Question: Chromium metal crystallizes as body-centered lattice. If the atomic radius of Cr is 1.25 Å, what is the density of Cr metal in g/cm3? 32. Question: Equation I shows phosphorous pentachloride preparation from PCl3 and Cl2: 33. Question: Using Hess's law of constant heat of summation and given: 34. Question: Calculate the temperature of 2.50 g CO2 gas occupies 5.60 liters at 789 torr in oC. 35. Question: What volume of O2(g), measured at 27 °C and 743 torr, is consumed in the combustion of 12.50 L of C2H6(g)?