1. Some more Regents Chemistry practice…

2. What is the empirical formula of C 3 H 6 ? A: CH D: CH 6 B: CH 2 C: CH 3

3. Empirical formula is the simplified version of a molecular formula… C 3 H 6 – divide by greatest common factor (3) to get CH 2 B

4. The name of the compound KClO 2, is potassium A: chlorine oxide D: perchlorateB: chlorite C: chlorate

5. ClO 2 – is a polyatomic ion since there is more than one capital letter… go to Table E and keep it as is B

6. What is the percent by mass of carbon in HC 2 H 3 O 2 (gram-formula mass is 60)? A: 12 / 60 * 100 D: 60 / 12 * 100B: 60 / 24 * 100 C: 24 / 60 * 100

7. Table T: % comp by mass = part / whole * 100 Since there are TWO carbon atoms…it is 24 / 60 * 100 Table T: % comp by mass = part / whole * 100 Since there are TWO carbon atoms…it is 24 / 60 * 100 C

8. What is the total volume occupied by 6.5 moles of CO 2 (g) ? A: 146 L D: 6.5 LB: 3.4 L C: 22.4 L

9. For ANY gas…1 mole occupies 22.4 L… 6.5 mol * 22.4 (L/mol) = 146 L A

10. The measure of the attraction for electrons in a chemical bond is A: ionization energy D: electronegativity B: atomic radius C: attractivity

11. Electronegativity… you can look up those values in Table S. Ionization energy is energy required to remove an electron. D

12. Given the equation: H 2 + Cl 2 → 2 HCl How many moles of HCl will be produced when 3 moles of H 2 is completely consumed? A: 3 moles D: 0.7 molesB: 2 moles C: 6 moles

13. H 2 + Cl 2 → 2 HCl Set up a ratio: eqn: 1 2 = ?: 3 x H 2 + Cl 2 → 2 HCl Set up a ratio: eqn: 1 2 = ?: 3 x C

14. What type of bond exists between an atom of carbon and an atom of fluorine? A: ionic D: nonpolar cov.B: metallic C: polar cov.

15. Has to be covalent because two nonmetals… Look up electronegativity values in Table S to see to that the difference is greater than 1. Polar: e - shared UNequally Nonpolar: e - shared equally C

16. Which is held together by metallic bonds? A: NaCl D: Br 2 B: Fe C: CO

17. Metallic bonding – look for the metal… Fe B

18. The primary forces of attraction between water molecules in H 2 O are A: ionic D: van der WaalsB: hydrogen C: molecule-ion

19. Water molecules held together by hydrogen bonding… remember surface tension? floating a razor blade? B

20. Which substance contains nonpolar covalent bonds? A: H 2 D: CaOB: H 2 O C: Ca(OH) 2

21. Covalent – must be two NONMETALS Nonpolar – electrons shared equally… electronegativity difference less than 1. A

22. What describes the electron dot structure of CaCl 2 ? A: brackets without charges D: no brackets, but charges B: no brackets, no charges C: brackets with charges

23. CaCl 2 is ionic (metal and nonmetal) so needs brackets AND charges… C CaCl [[[]]] +2 (lost 2 e-) (gained 1 e-)

24. Which statement best describes the following reaction? Cl + Cl → Cl 2 + energy A: bond formed & energy released D: bond broken & energy absorbed B: bond broken & energy released C: bond formed & energy absorbed

25. Two reactants become one product… bond is formed Energy is on the product side… energy is released A

26. The modern model of the atom shows that electrons are A: orbiting nucleus in fixed paths D: located in a solid sphere covering nucleus B: combined with neutrons in the nucleus C: found in regions called orbitals

27. Modern model of atom = wave-mechanical model OR electron cloud model… orbital = probable locations of e - C

28. What is atomic number of an element that has 6 protons and 8 neutrons? A: 6 D: 14B: 2 C: 8

29. Atomic number = number of protons A

30. What is the total number of protons contained in the nucleus of a carbon-14 atom? A: 6 D: 14B: 8 C: 12

31. The “14” in carbon-14 represents the mass number (protons + neutrons). If the atom is carbon… look up its atomic number. A

32. Which of these elements has an atom with the most stable outer electron configuration? A: Ca D: NeB: Cl C: Na

33. Look for the noble gases in group 18… They have full valence shells. (2 e - for He, 8 e - for the rest) D

34. What is the nuclear charge of an iron atom? A: +30 D: +82B: +26 C: +56

35. Protons and neutrons are in nucleus. Protons are positive and neutrons are neutral...making the charge on the nucleus positive. Look up atomic number of iron = 26. B

36. How many electrons are in the outermost principal energy level of an atom of bromine in the ground state? A: 35 D: 8B: 7 C: 2

37. Look up the number of valence e - … Electron config: 2-8-18-7 Valence e - are last number = 7… Group 17 has 7 valence e -. B

38. Which electron configuration is correct for a sodium ion? A: 2-7 D: 2-8-2B: 2-8-1 C: 2-8

39. Na electron config as an ATOM is 2-8-1 It is in group 1 and will lose its 1 valence e - to become stable. C

40. The nucleus of which atom contains 48 neutrons? 32 A: S 16 112 D: Cd 48 B: Ti 22 85 C: Rb 37

41. Mass number is top number = protons + neutrons Atomic number is bottom number = number of protons (protons + neutrons) – (protons) = NEUTRONS C

42. When an atom loses an electron, the atom becomes an ion that is A: (+) and larger D: (-) and smaller B: (-) and larger C: (+) and smaller

43. Losing e-… (+) charge (look at oxidation state) When you lose weight, for example, you become smaller… the same goes for atoms & ions. C

44. Spectral lines of elements are caused when electrons in an excited state move from A: low to high energy levels, absorbing energy D: high to low energy levels, releasing energy B: high to low energy levels, absorbing energy C: low to high energy levels, releasing energy

45. An atom absorbs energy…electron jumps to higher energy level. (excited state) When the electron falls back to a lower energy level, energy is released in the form of light. (back to ground state) D

46. What happens when NaCl is dissolved in water? A: Na + ions attracted to O atoms of water D: Cl - ions are repelled by the H atoms of water B: Na + ions are repelled by the O atoms of water C: Cl - ions attracted to O atoms of water

47. Oxygen atoms have a partial negative charge so the Na + ions are attracted to that side of the water molecule. A

48. According to Table G, which solution at equilibrium contains 50 g of solute per 100 g of water at 75˚C? A: unsaturated solution of KCl D: saturated solution of KClO 3 B: saturated solution of KCl C: unsaturated solution of KClO 3

49. Saturated solution is when falls right on the curve. Go over to 75 degrees and up to 50 g of solute. B

50. Which compound is least soluble in 100 g of water at 40 ˚C ? A: SO 2 D: NH 4 ClB: NaCl C: KClO 3

51. When you go over to 40 degrees and then up… SO 2 is the first solute you run into, which means it is the least soluble. A

52. What is the total number of moles of solute in 2.0 L of 3.0 M NaOH? A: 6 moles D: 1 moleB: 2 moles C: 3 moles

53. When you see “M” head to Table T: molarity = (moles) / (liters) x 3 = 2 A

54. Real gases are like ideal gases at A: high pressure & low temp D: low pressure & high temp B: low pressure & low temp C: high pressure & high temp

55. At high temps, particles move fast and have less chance of attracting each other… At low pressure, particles won’t be so “squished” together and will be less likely to attract each other. D

56. As the temperature of a given sample of gas decreases at constant pressure, the volume of the gas A: decreases D: smellsB: remains the same C: increases

57. Temperature and volume have a direct relationship… they both increase or they both decrease. A

58. 2.0 L of CH 4 and 2.0 L of O 2 have the same A: density D: # of atomsB: # of molecules C: mass

59. They have the same volume so… they have the same # of molecules since they have the same # of moles. (6.02 x 10 23 molecules in a mole) B

60. Which phase is endothermic? A: gas → solid D: liquid → gas B: gas → liquid C: liquid → solid

61. Endothermic… absorb energy. A liquid must absorb energy to become a gas. D

62. What happens to average kinetic energy if temperature is increased? A: increases B: decreases C: remains the same

63. Think of average kinetic energy and temperature as the same thing… A

64. What happens to temperature as water freezes? A: decreases B: increases C: remains the same

65. Temperature (average kinetic energy) remains the same during a phase change… only potential energy changes during a phase change. C

66. Elements in a given period contain the same number of A: protons D: # of energy levels B: neutrons C: valence e-

67. Going across period 4… every element has 4 energy levels. Examples: 2-8-8-1 & 2-8-18-6 D

68. Atoms of metals tend to A: lose e - and form (-) ions D: gain e - and form (+) ions B: lose e - and form (+) ions C: gain e - and form (-) ions

69. Metals only have a few valence e - and want to lose e -. Look at the oxidation for metals… they are positive. B

70. Which two elements have chemical properties that are most similar? A: Cl and Ar D: C and NB: Li and Na C: K and Ca

71. Elements in the same group have the same # of valence e -. Elements with the same # of valence e - have similar chemical properties. B

72. If M represents an alkali metal, what is the formula for the compound formed by M and oxygen? A: MO 2 D: M 3 O 2 B: M 2 O C: M 2 O 3

73. Alkali metals = Group 1… Group 1 form + 1 ions M +1 O -2 …criss-cross… M 2 O B

74. As elements of Group 15 are considered from top to bottom, the metallic character of the atoms A: increases B: decreases C: remains the same

75. Metallic character increases as you go down a group. A

76. Which Group 15 element exists as a diatomic molecule at STP? A: phosphorus D: arsenicB: bismuth C: nitrogen

77. Remember “HOF BrINCl”? Hydrogen, oxygen, fluorine, bromine, iodine, nitrogen, chlorine C

78. Properties of nonmetal atoms include A: low ionization energy and low electronegativity D: high ionization energy and high electronegativity B: low ionization energy and high electronegativity C: high ionization energy and low electronegativity

79. Ionization energy = energy required to remove e -. High ionization energy because nonmetals want to GAIN, not lose e -. Electronegativity = attraction for e - when in a bond. High electronegativity because nonmetals “pull harder” on e -. JUST USE TABLE S!!! D

80. A redox reaction always demonstrates the conservation of A: mass D: both mass and charge B: neither mass or charge C: charge

81. Both mass and charge will be conserved. D

82. What occurs when an atom is oxidized? A: loss of e- and an increase in oxidation number D: gain of e- and a decrease in oxidation number B: loss of e- and a decrease in oxidation number C: gain of e- and an increase in oxidation number

83. GGGRRRRR…. Gain = reduction (charge reduced) Lose = oxidation (charge icnreases – think of when metals lose e - ) A

84. An electrochemical setup consists of two half-cells, an anode, a cathode, an external circuit, and a salt bridge. When a rxn occurs, ion migration takes place through the? A: anode D: external circuit B: cathode C: salt bridge

85. Ions pass through salt bridge… Electrons pass through external circuit. C

86. The decomposition of water is forced to occur by use of an externally applied electric current. This procedure is called A: neutralization D: hydrolysisB: electrolysis C: esterification

87. If an outside power source is needed to get a chemical reaction to occur, it must be an electrolytic cell. Decomposing water is called… electrolysis. B

88. Which description is correct for a voltaic cell? A: spontaneous & anode is (-) D: nonspontaneous & anode is (+) B: nonspontaneous & anode is (-) C: spontaneous & anode is (+)

89. Voltaic cells do NOT need an outside power source, which means they are spontaneous. VAN…voltaic anode is negative. (opposite for electrolytic) A

90. Given the reaction: Zn + HCl → ZnCl 2 + H 2 The oxidation number of H +1 decreases because it A: loses protons D: gains electronsB: gains protons C: loses electrons

91. If charge decreases, H +1 must have been reduced. Remember gaining negative electrons makes it more negative. D

92. Which reaction occurs when equivalent quantities of H + and OH - are mixed? A: oxidation D: hydrolysisB: reduction C: neutralization

93. Equal amounts of hydrogen ions and hydroxide ions makes a solution neutral…pH = 7. C

94. What is the pH of a 0.01 M solution of KOH? A: 1 D: 13B: 2 C: 12

95. Two steps: 1. KOH is a base…[OH - ] = 0.01 so pOH is 2. 2. 14 – pOH = pH 14 – 2 = 12 Two steps: 1. KOH is a base…[OH - ] = 0.01 so pOH is 2. 2. 14 – pOH = pH 14 – 2 = 12 C

96. The [H 3 O + ] of a solution is 1 x 10 -8. This solution has a pH of A: 6, which is acidic D: 8, which is acidic B: 8, which is basic C: 6, which is basic

97. [H 3 O + ] is the hydronium ion… think of it like the H + ion. Just take the exponent and that will be the pH…8. 0 – 7 is acidic 7 – 14 is basic B

98. How many mL of 0.20 M KOH are needed to completely neutralize 90.0 mL of 0.10 M HCl? A: 25 mL D: 180 mL B: 45 mL C: 90 mL

99. Table T…titration equation. M A V A = M B V B (0.1) * (90) = (0.2) * X B

100. If a given solution contains [H + ] = 1 x 10 -9, what is the [OH - ]? A: 1 x 10 -5 D: 1 x 10 -1 B: 1 x 10 -9 C: 1 x 10 -14

101. The exponents need to add up to 14… 1 x 10 -5 A

102. Which compound is a strong Arrhenius base? A: C 2 H 5 OH D: NaOH B: CH 3 OH C: HOH

103. Go to Table L for bases and Table K for acids… they are usually in those tables. HOH is water, both CH 3 OH and C 2 H 5 OH are alcohols. D

104. Methyl orange is used to test a solution. If it turns red, what could the pH value be? A: 3.0 D: 8.6 B: 4.0 C: 4.4

105. Go to Table M for indicator questions. 3.2 - 4.4 red - orange - yellow A

106. Which statement best describes the solution produced when an Arrhenius acid is dissolved in water? A: only (-) ion in solution is OH - D: only (-) ion in solution is HCO 3 - B: only (+) ion in solution is H + C: only (+) ion in solution is NH 4 +

107. Acids produce [H + ] ions…. Bases produce [OH - ] ions. B

108. Which formula represents a saturated compound? A: C 2 H 4 D: C 3 H 8 B: C 3 H 6 C: C 2 H 2

109. Only alkanes are saturated… saturated hydrocarbons have the most hydrogens possible… the compound needs all single bonds. D

110. What describes two isomers of a hydrocarbon? A: same formula, same structure D: different formula, same structure B: different formula, different structure C: same formula, different structure

111. Isomers have the same formula, but the atoms are arranged differently. Two isomers of pentane will both have 5 carbons and 12 hydrogens… they will just be arranged differently. C

112. What is the maximum number of covalent bonds that can be formed by one carbon atom? A: 1 D: 4B: 2 C: 3

113. Carbon has 4 valence electrons and will need to form 4 bonds to complete its valence shell. D

114. A compound with the formula CH 3 CH 2 OH is classified as an A: alkane D: acidB: alcohol C: alkene

115. Table R… the –OH functional group makes it an alcohol. B

116. How many bromine atoms are in the compound 1,1-dibromopropane? A: 1 D: 4B: 2 C: 3

117. Di- means 2. The “1,1” tells you location of each of the bromine atoms. So you can count the numbers also. B

118. Which formula represents ethanoic acid? A: CH 3 CHO D: CH 3 CH 2 CHOB: CH 3 CH 2 COOH C: CH 3 COOH

119. Eth- means two carbons. Table R… -COOH functional group means organic acid. C

120. What is the name of the chemical reaction when glucose decomposes into carbon dioxide and ethanol? A: fermentation D: combustionB: addition C: substitution

121. Fermentation… decomposition would also work. A

122. When radium-226 undergoes natural transmutation, it emits A: an alpha particle B: a beta particle C: a position D: a neutron

123. Table N… find radium-226 and look for decay mode. A

124. Which type of radiation has zero mass and zero charge? A: alpha B: beta C: gamma D: neutron

125. Table O... 0 γ 0 C

126. What type of radiation has the weakest penetrating power? A: alpha B: beta C: gamma D: neutron

127. Alpha particles are big and slow and won’t pass through paper. A

128. What type of radiation has the weakest In how many days will a 12 g sample of iodine-131 decay, leaving 1.5 g of the original isotope? A: 8 B: 16 C: 20 D: 24

129. Four half-lives… 1: 12 – 6 2: 6 – 3 3: 3 – 1.5 D