CHM 134 General Chemistry I Name KEY Exam I Fall 2005 1pt Section I: Multiple Choice. (1.5 points each) 1. Which of the following is a heterogeneous mixture? a) mortar (a mixture of calcium carbonate and sand) 2. A pure substance composed of two or more different elements is e) a chemical compound. 3. What is the name of the element with the symbol B? a) boron 4. What is the name of the element with the symbol Ca? c) calcium 5. Which term best describes oxygen gas, O 2? c) element 6. All of the following are examples of physical properties EXCEPT b) aluminum oxidizes to form Al 2 O 3. 7. All of the following are examples of chemical change EXCEPT d) the condensation of steam. 8. The boiling point of liquid helium is 4 K. What is this temperature in Celsius? c) -269 ºC 9. What is the correct answer to the following expression: (72.61 68.59) 18.76? c) 75.4 10. What is the correct answer to the following expression: (18 + 95) 0.077351? b) 8.74
11. Which method is correct for determining the liters of gas required to fill an automobile s 15 gallon tank? (1.000 L = 1.057 quarts, 4 quarts = 1 gallon) 4 quarts 1 liter c) 15 gallons = 1 gallon 1.057 quarts 12. What is the correct answer to the following expression: 2.97 10-5 + 6.13 10-3? b) 6.16 10-3 13. Alpha particles (α) are c) helium nuclei. 14. Beta (β) particles are identical to. b) electrons 15. What is the atomic symbol for an element with 28 protons and 31 neutrons? a) 59 28 Ni 16. What is the identity of 72 32 X? d) Ge 17. What is the atomic symbol for an element that has 30 neutrons and a mass number of 55? e) Mn 18. Which two of the atoms below have the same number of neutrons? 64 63 64 68 28 Ni, 29Cu, 30Zn, Zn? 30 a) 63 64 29Cu and Zn 30 19. Which two of the following atoms are isotopes? 45 48 50 21Sc, 22Ti, Ti, 50 V 22 23 b) 48 50 22Ti and Ti 22 20. Calculate the number of moles in 0.41 g titanium. b) 8.6 10-3 mol
21. What is the mass of 5.1 mol P? d)1.6 10 2 g 22. A 3.6 g sample of lithium contains atoms. c) 3.1 10 23 23. Which three elements are likely to have similar chemical and physical properties? a) sodium, lithium, and potassium Section II: Fill in the blank. (1.5 points each) 24. Pure carbon can exist in several forms, or allotropes. Examples include diamond, graphite, and buckminsterfullerene. 25. The group 2 (or 2A) elements are also known as the alkaline earth metals. 26. An atom of cobalt-59 has 32 neutrons. 27. The term accuracy refers to the nearness of a result to the true result. 28. Nitrogen is the largest component of the air we breathe. Particles of this substance exist as _diatomic molecules. 29. The two elements that are found as liquids at room temperature and atmospheric pressure are mercury and _bromine. 30. When this fourth period element is placed in water, a violent reaction ensues. The element is _potassium.
Section III: Solve each problem, showing your work in order to receive full credit. 31. (5 points) What mass of He contains the same number of atoms as 5.00 g Kr? 4.003 g He/mole 5 g Kr = 83.8 g Kr/mole 0.239 g He 32. (5 points) The density of iron is 7.87 g/cm 3. Calculate the number of iron atoms present in a cube that has an edge length equal to 3.00 cm. 23 7.87 g 3 1 mole Fe 6.022 10 atoms Fe 27 cm 3 cm 55.85 g Fe mole Fe = 24 2.29 10 atoms Fe 33. (10 points) A gallon (3.78 L) of latex paint can cover 385 ft 2 of the surface of a wall. What is the average thickness of one coat of paint (in micrometers)? 3 2 2 4 3780 cm ft in 1 10 µ m = 2 2 2 385 ft 144 in 6.4516 cm cm 106 µ m
34. (10 points) Bromine has two naturally occurring isotopes. The average mass of bromine is 79.904 u. If 50.54% of bromine is found as bromine-79 (78.9183 u), what is the mass of the other isotope? 79.904 = (.5054 78.9183) + (.4946 x) 79.904.5054 78.9183 x = =.4946 80.91 u 35. (4 points) Everything that is matter can be classified as one of four things. What are the four things? heterogeneous matter solution element compound 36. (10 points) Matching A_ density A. an intensive property D_ electron charge B. an extensive property J transition metals C. Thomson s Cathode Ray Experiment F Periodic Table D. Mullikan s Oil Drop Experiment B volume E. Rutherford s Gold Foil Experiment E highly dense nucleus F. Mendelev s similarities of elements H mole G. mass spectrometer C electron charge/mass H. Avogadro s number G isotopes I. partially metallic I metalloids J. Fe, for example
37. (.5 points each) Element names and Symbols Provide the correct element symbol for these: platinum Pt chlorine Cl tin Sn xenon Xe uranium U phosphorus P mercury Hg manganese Mn boron B _ silver Ag Provide the correctly spelled element name for these: Zn zinc As arsenic F fluorine Fe iron W tungsten Na sodium Be beryllium Ar argon Sb antimony Si silicon