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?