1. Some more Regents Chemistry practice…

2. What is the empirical formula of C3H6?
A: CH
C: CH3
B: CH2
D: CH6

3. B
Empirical formula is the simplified version of a molecular formula… C3H6 – divide by greatest common factor (3) to get CH2

4. The name of the compound KClO2, is: potassium…
A: chlorine oxide
C: chlorate
B: chlorite
D: perchlorate

5. B
ClO2– is a polyatomic ion since there is more than one capital letter… look in Table E

6. What is the percent by mass of carbon in HC2H3O2 (gram-formula mass is 60)?
D: 60 / 12 * 100

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

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

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

10. Given the equation: H2 + Cl2 → 2 HCl How many moles of HCl will be produced when 3 moles of H2 is completely consumed?
A: 3 moles
C: 6 moles
B: 2 moles
D: 0.7 moles

11. C
H2 + Cl2 → 2 HCl If 1 mole H2 makes 2 moles HCl, then 3 moles H2 makes…

12. What type of bond exists between the atoms in CF4?
A: ionic
C: polar cov.
B: metallic
D: nonpolar cov.

13. C
Has to be covalent because two nonmetals… Polar: e- shared UNequally Nonpolar: e- shared equally

14. Which is held together by metallic bonds?
A: NaCl
C: CO
B: Fe
D: Br2

15. Metallic bonding – look for the metal… Fe

16. What is the primary force of attraction between water molecules in H2O ?
A: ionic bonding
C: molecule-ion attraction
B: hydrogen bonding
D: dispersion forces

17. Water molecules are held together by hydrogen bonding

18. Which substance contains nonpolar covalent bonds?
A: H2
C: Ca(OH)2
B: H2O
D: CaO

19. Covalent – must be two NONMETALS Nonpolar – electrons shared equally…

20. Which statement best describes the following reaction
Which statement best describes the following reaction? Cl + Cl → Cl2 + energy
A: bond formed & energy released
C: bond formed & energy absorbed
B: bond broken & energy released
D: bond broken & energy absorbed

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

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

23. C
Wave-mechanical model OR electron cloud model… orbital = probable locations of e-

24. What is atomic number of an element that has 6 protons and 8 neutrons?

25. Atomic number = number of protons

26. What is the total number of protons contained in the nucleus of a nitrogen-14 atom?

27. If the atom is nitrogen… look up its atomic number.

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

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

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

31. B
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.

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

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

34. Which electron configuration is correct for a sodium ion?B: D:

35. C
Sodium electron configuration as an ion is It is in group 1 and will lose its 1 valence e- to become stable.

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

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

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

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

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

41. D
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)

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

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

44. 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
C: unsaturated solution of KClO3
B: saturated solution of KCl
D: saturated solution of KClO3

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

46. Which compound is least soluble in 100 g of water at 40˚C?
A: SO2
C: KClO3
B: NaCl
D: NH4Cl

47. A
When you go over to 40 degrees and then up… SO2 is the first solute you run into, which means it is the least soluble.

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

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

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

51. D
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.

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

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

54. 2.0 L of CH4 and 2.0 L of O2 have the same
A: density
C: mass
B: # of molecules
D: # of atoms

55. B
They have the same volume so… they have the same # of moles, so they have the same # of molecules (6.02 x 1023 molecules in a mole)

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

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

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

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

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

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

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

63. D
Going across period 4… every element has 4 energy levels. Examples: &

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

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

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

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

68. If M represents an alkali metal, what is the formula for the compound formed by M and oxygen?
A: MO2
C: M2O3
B: M2O
D: M3O2

69. Alkali metals = Group 1… Group 1 form +1 ions M+1O-2 M2OB
Alkali metals = Group 1… Group 1 form +1 ions M+1O-2 M2O

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

71. Metallic character increases as you go down a group.

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

73. C
Remember the “7H Club” Nitrogen, oxygen, fluorine, chlorine, bromine, iodine, hydrogen

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

75. D
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!!!

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

77. Both mass and charge will be conserved.

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

79. A
Oil Rig oxidation is losing electrons (charge increases) Reduction is gaining electrons (charge decreases)

80. A: anode C: salt bridge B: cathode D: wire
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
C: salt bridge
B: cathode
D: wire

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

82. The decomposition of water is forced to occur by use of an externally applied electric current. This procedure is called
A: neutralization
C: synthesis
B: electrolysis
D: hydrolysis

83. B
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.

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

85. A
Voltaic cells do NOT need an outside power source, which means they are spontaneous. Oxidation = anode = negative

86. Given the reaction: Zn + HCl → ZnCl2 + H2 The oxidation number of H+1 decreases because it…
A: loses protons
C: loses electrons
B: gains protons
D: gains electrons

87. D
If charge decreases, H+1 must have been reduced. Remember gaining negative electrons makes it more negative (or less positive).

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

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

90. What is the pH of a 0.01 M solution of HCl?
B: 2
D: 13

91. HCl is an acid…[H+] = 0.01 = 1 x 10-2 pH is 2.

92. The [H3O+] of a solution is 1 x 10-8. This solution has a pH of
A: 6, which is acidic
C: 6, which is basic
D: 8, which is acidic
B: 8, which is basic

93. B
[H3O+] 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 – 14 is basic

94. How many mL of 0. 20 M KOH are needed to completely neutralize 90
How many mL of 0.20 M KOH are needed to completely neutralize 90.0 mL of 0.10 M HCl?
A: 25 mL
C: 90 mL
D: 180 mL
B: 45 mL

95. Table T…titration equation. MAVA = MBVB (0.10) * (90) = (0.20) * X

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

97. A
[H+] x [OH-] = 1 x 10-14

98. Which compound is a strong Arrhenius base?
A: C2H5OH
C: HOH
D: NaOH
B: CH3OH

99. D
Go to Table L for bases and Table K for acids… they are usually in those tables. HOH is water, both CH3OH and C2H5OH are alcohols.

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

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

102. Which statement best describes the solution produced when an Arrhenius acid is dissolved in water?
C: only (+) ion in solution is NH4+
A: only (-) ion in solution is OH-
D: only (-) ion in solution is HCO3-
B: only (+) ion in solution is H+

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

104. Which formula represents a saturated compound?
A: C2H4
C: C2H2
B: C3H6
D: C3H8

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

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

107. C
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.

108. What is the maximum number of covalent bonds that can be formed by one carbon atom?

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

110. A compound with the formula CH3OCH3 is classified as an
A: aldehyde
C: ketone
B: ether
D: acid

111. Table R… the –O- functional group makes it an ether.

112. How many bromine atoms are in the compound 1,1,2-tribromopropane?

113. C
Tri- means 3. The “1,1,2” tells you location of each of the bromine atoms. So you can count the numbers also.

114. Which formula represents ethanoic acid?
A: CH3CHO
C: CH3COOH
B: CH3CH2COOH
D: CH3CH2CHO

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

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

117. Fermentation… decomposition would also work.

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

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

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

121. C
Table O γ 0

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

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

124. In how many days will a 12 g sample of iodine-131 decay, leaving 1
In how many days will a 12 g sample of iodine-131 decay, leaving 1.5 g of the original isotope?
A: 8
C: 20
D: 24
B: 16

125. Three half-lives… 1: 12 – 6 2: 6 – 3 3: 3 – 1.5D
Three half-lives… 1: 12 – 6 2: – 3 3: 3 – 1.5