Chemistry 12 Test

Chemistry 12 Test Modified True/False Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the sentence or statement true. ____ 1. Transition metals are monovalent because they attempt to get more stable electron configurations like half-filled and empty orbitals. ____________________ ____ 2. Absorption spectra are the result of energy that has been absorbed by electrons. ____________________ ____ 3. Electrons are most likely found near the nucleus, regardless of the type of orbital they 'occupy'. ____________________ ____ 4. The Pauli exclusion principle requires that two electrons in the same orbital have the same spin. ____________________ ____ 5. All of the valence electrons in Fe2+ must have the same spin. _________________________ ____ 6. A laser produces monochromatic light. _________________________ ____ 7. Carbon tetrafluoride, CF4, contains four polar bonds and is a polar molecule. _________________________ ____ 8. Diamond does not conduct electricity because it contains delocalized electrons. ______________________________ ____ 9. Water is adhesive because it is bi-polar. _________________________ ____ 10. A dipole occurs when two atoms with similar electronegativities bond to each other. _________________________ ____ 11. Energy transformations are the basis for all the activities that make up our lives. ____________________ ____ 12. Thermal energy is a form of potential energy that can be released to the surroundings. ____________________ ____ 13. A negative enthalpy change is a measure of the amount of energy absorbed from the surroundings. ____________________ ____ 14. Inside a calorimeter, the amount of energy gained by the surroundings (the water) must equal the amount of energy released by the reaction in the calorimeter. _____________________ ____ 15. The enthalpy change per mole of a substance undergoing a change is called the molar enthalpy. ____________________ ____ 16. Enthalpy changes for an exothermic reaction are given a negative sign. ____________________ ____ 17. Enthalpy changes for an endothermic reaction are given a negative sign. ____________________ ____ 18. If a chemical equation is reversed, according to Hess's Law, no change occurs to the ?H of the reaction. ____________________ ____ 19. To date there have been no major nuclear accidents in Canada. ____________________ ____ 20. Half-life is the time required for one half of the sample to react. _________________________ Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. ____ 21. The arrangement of electrons around the nucleus of an atom is known as a. the Bohr model d. the diagonal rule b. the ground state e. the electron configuration c. the principal quantum number ____ 22. The 3p atomic orbital has the shape of a. a sphere d. two perpendicular dumb-bells b. a torus e. an egg c. a dumb-bell ____ 23. Which of the following elements would have the lowest first ionization energy? a. sodium d. chlorine b. aluminum e. argon c. nitrogen ____ 24. Unlike Bohr's model of the atom, the quantum mechanical model of the atom treats the electron like a. a tiny particle d. a wave b. a proton e. a photon c. a positive particle ____ 25. Why is phosphorus able to have a valence of 5+? a. it is in group 5 b. it has five valence electrons c. its most easily removed electron is in a p orbital d. it has empty d orbitals e. none of the above ____ 26. Why do non-metals have high electronegativities? a. they are very small atoms and thus have a stronger hold on their electrons b. they are on the left side of the periodic table c. they contain many protons therefore they have a stronger hold on their electrons d. they can easily become iso-electronic with noble gases by accepting electrons e. none of the above ____ 27. Which element is the most electronegative? a. helium d. hydrogen b. fluorine e. sodium c. francium ____ 28. Which atoms could have the valence electron configuration shown below? ?? ???????? s p a. N3- d. Cl1- b. O2- e. all of the above c. Ar ____ 29. Which of the following is the electron configuration for calcium, Ca? a. 1s22s22p63s23p64s2 d. 1s22s22p63s23p6 b. 1s22s22p63s2 e. 1s22s2 c. 1s22s22p6 ____ 30. Which technology demonstrates the principles of quantum mechanics? a. laser d. MRI b. spectrophotometer e. all of the above c. X-ray machine ____ 31. In which of the following situations is a spectrophotometer a useful instrument? a. producing new substances d. microsurgery b. producing high energy photons e. all of the above c. detecting trace amounts of substances ____ 32. Which technology seems to challenge our understanding of quantum mechanics? a. superconductors d. semi-conductors b. lasers e. X-ray machines c. spectrophotometers ____ 33. A solid is soft and has a low melting point. It does not conduct electricity. What type of solid is it? a. metallic solid d. molecular crystal b. ionic crystal e. plasma c. covalent solid ____ 34. Which shape and bond angle are predicted by VSEPR theory for H2O? a. linear, 180o d. bent, 109.5o b. bent, 120o e. bent, less than 109.5o c. bent, less than 120o ____ 35. What is the basis of metallic bonding? a. the attraction of metal ions for delocalized electrons b. the attraction between neutral metal ions c. the neutralization of protons by electrons d. the attraction of oppositely charged ions e. the sharing of two valence electrons between two atoms ____ 36. Which of the following bonds is likely to exhibit the greatest ionic character? a. H-F d. Cl-Cl b. F-F e. Cl-F c. H-Cl ____ 37. Which of the molecules, CO2, H2O, NH3, and BF3, will be polar? a. CO2, NH3 and BF3 d. CO2, H2O and NH3 b. H2O and NH3 e. CO2 and BF3 c. H2O and BF3 ____ 38. What would be the shape of a molecule containing a central atom attached to five other atoms with one lone pair of electrons? a. trigonal pyramidal d. square pyramidal b. trigonal planar e. octahedral c. square planar ____ 39. Which forces exist between methane, CH4 particles? I. Van der Waals II. metallic bonding III. hydrogen bonding IV. dipole a. I only d. I, III and IV only b. I and IV only e. I, II and III only c. I and II only ____ 40. Which forces exist between iron, Fe, particles? I. Van der Waals II. metallic bonding III. hydrogen bonding IV. dipole a. I only d. I, III and IV only b. I and IV only e. I, II and III only c. I and II only ____ 41. Which statement is the best description of potassium chloride, KCl? a. polar molecule d. ionic compound b. polar bonds, non polar molecule e. none of the above c. non polar molecule ____ 42. What type of substance is hydrogen sulfide, H2S? a. ionic d. metallic b. molecular e. none of the above c. covalent network ____ 43. What type of substance is methane, CH4? a. ionic d. metallic b. molecular e. none of the above c. covalent network ____ 44. What is the shape of hydrogen cyanide, HCN? a. linear d. octahedral b. trigonal planar e. trigonal pyramid c. tetrahedral ____ 45. What is the shape of sulfur hexahydride, SH6? a. linear d. octahedral b. trigonal planar e. trigonal pyramidal c. tetrahedral ____ 46. In an exothermic reaction, heat flows into the surroundings because a. the potential energy of the chemicals increases b. the kinetic energy of the chemicals decreases c. the chemical potential energy is converted into heat energy d. the chemical kinetic energy is converted into heat energy e. none of the above ____ 47. A chemical system in which both energy and matter can flow into or out of a system is described as a. a closed system d. a chemical system b. an open system e. none of the above c. an isolated system ____ 48. An enthalpy change is a. the difference in the kinetic energy of the reactants and the products in a chemical change b. the difference in the potential energy of the reactants and the products in a chemical change c. the difference in enthalpies of the reactants and the products in a chemical change d. the sum of the potential and kinetic energies of the products e. the sum of the potential and kinetic energies of the reactants ____ 49. When a 'target' reaction can be expressed as the sum of other reactions, the heat of the 'target' reaction is the sum of the enthalpy changes of the other reactions. This statement is referred to as a. Law of Constant Composition d. Priestly's Law b. Law of Conservation of Energy e. Boyle's Law c. Hess's Law ____ 50. The combustion of magnesium in air is very exothermic. If the given two reactions and their heats of reaction were used to determine the heat of combustion of magnesium the result would be a. x + y d. x – 2y b. x – y e. not enough information is given c. 2x – y ____ 51. Within a reaction with 2 reactants and 2 products, the reaction rate can be measured with respect to a. all 4 substances d. only 1 of the substances b. 3 of the substances e. not enough information to determine c. 2 of the substances ____ 52. The presence of a catalyst is thought to increase the rate of a reaction by a. changing the products that are formed in the reaction b. decreasing the enthalpy change of the reaction c. increasing the enthalpy change of the reaction d. decreasing the activation energy of the reaction e. increasing the activation energy of the reaction ____ 53. The following graph represents a reaction of order a. 0 d. 3 b. 1 e. 4 c. 2 ____ 54. The following graph represents a reaction of order a. 0 d. 3 b. 1 e. 4 c. 2 ____ 55. The following graph represents a reaction of order a. 0 d. 3 b. 1 e. not enough information c. 2 ____ 56. The amount of energy required for a reaction to begin is known as a. enthalpy change d. kinetic energy b. reaction energy e. potential energy c. activation energy ____ 57. The activated complex a. is an unstable molecule b. has the maximum potential energy possible c. may continue on to produce products d. may revert to reactants e. all of the above ____ 58. If a reaction can be broken down into a reaction mechanism, then the steps of the reaction mechanism are known as a. stages of reaction d. elementary steps b. activated complexes e. primary equations c. reaction progress ____ 59. Reaction mechanisms a. are easily determined b. cannot be determined without knowing the enthalpy of the reaction c. are only 'best guesses' at the behaviour of molecules d. do not need to represent the whole reaction e. do not involve any reaction intermediates ____ 60. The theoretical effect of an increase in temperature can be explained in terms of collision theory because it affects I. the collision geometry involved in the reaction II. the total number of collisions that occur III. the fraction of collisions that are effective IV. the required activation energy for a reaction a. both I and IV d. both III and IV b. I, II and III are true e. II only c. both II and III Completion Complete each sentence or statement. 61. ____________________ orbitals are non-directional. 62. The "1" in helium's (He) electron configuration represents the ____________________. 63. The shape of sulfur dioxide would most likely be ____________________. 64. The metal ions in a metallic solid are surrounded by delocalized electrons because metals have low _________________________. 65. VSEPR theory predicts the ____________________ of molecules. 66. The electrostatic forces between ions in ionic compounds cause ____________________ boiling points. 67. A _________________________ is obtained by measuring the rate of product formation or the rate at which a reactant is consumed. 68. The rate of consumption of a reactant is fastest at the ____________________ of the reaction 69. The rate of a reaction that produces ions can be measured by measuring the change in its ____________________. 70. An enzyme, a protein in living cells, acts like a _________________________ to control the rate of a specific biochemical reaction. Matching Match these thermochemical terms with the following statements. a. thermal energy h. open system b. chemical system i. isolated system c. surroundings j. closed system d. heat k. calorimetry e. exothermic l. bomb calorimeter f. enthalpy change m. endothermic g. temperature n. molar enthalpy ____ 71. all matter around a system that is capable of absorbing or releasing thermal energy ____ 72. amount of energy transferred between substances ____ 73. a system in which energy can move in or out, but not matter ____ 74. a device in which a fuel is burned inside an insulated container to measure heat transfer during chemical reactions ____ 75. energy available from a substance as a result of the motion of its molecules ____ 76. a set of reactants and products under study, usually represented by a chemical equation ____ 77. an ideal system in which neither matter nor energy can move in or out ____ 78. average kinetic energy of the particles in a sample of matter ____ 79. the difference in enthalpies of reactants and products during a reaction ____ 80. the enthalpy change involving one mole of a substance Short Answer 81. Diamond and graphite are both composed entirely of carbon. Use diagrams to explain why they have different physical properties. 82. Predict the shape of a central atom surrounded by four other atoms and two unbonded pairs of electrons. Explain your reasoning using VSEPR theory. 83. Explain the purpose of a catalytic converter on an automobile. 84. Define the term half-life. Give an example. 85. How can the effect of concentration on the reaction rate be explained by collision theory?