SAT Subject Test Chemistry

PART 3

PRACTICE TESTS

Practice Test 2

Note: For all questions involving solutions and/or chemical equations, assume that the system is in water unless otherwise stated.

Reminder: You may not use a calculator on these tests.

The following symbols have the meanings listed unless otherwise noted.

H = enthalpy

T = temperature

L = liter(s)

M = molar

V = volume

mL = milliliter(s)

n = number of moles

atm = atmosphere

mm = millimeter(s)

P = pressure

g = gram(s)

mol = mole(s)

R = molar gas constant

J = joules(s)

V = volt(s)

S = entropy

kJ = kilojoules

 

Part A

Directions: Every set of the given lettered choices below refers to the numbered statements or formulas immediately following it. Choose the one lettered choice that best fits each statement or formula and then fill in the corresponding oval on the answer sheet. Each choice may be used once, more than once, or not at all in each set.

Questions 1–4 refer to the following terms:

(A) Law of Definite Composition

(B) Nuclear fusion

(C) van der Waals forces

(D) Graham’s Law of Diffusion (Effusion)

(E) Triple point

1. At a particular temperature and pressure, three states of a substance may coexist.

2. The combining of nuclei to release energy.

3. The ratio of the rate of movement of hydrogen gas compared with the rate of oxygen gas is 4 : 1.

4. The molecules of nitrogen monoxide and nitrogen dioxide differ by a multiple of the mass of one oxygen.

Questions 5–7 refer to the following diagram:

5. The of the reaction to form CO from C + O2

6. The of the reaction to form COfrom CO + O2

7. The of the reaction to form COfrom C + O2

Questions 8–11

(A) Hydrogen bond

(B) Ionic bond

(C) Polar covalent bond

(D) Nonpolar covalent bond

(E) Metallic bond

8. The type of bond between atoms of potassium and chloride when they form a crystal of potassium chloride

9. The type of bond between the atoms in a nitrogen molecule

10. The type of bond between the atoms in a molecule of CO(electronegativity difference = 1)

11. The type of bond between the atoms of calcium in a crystal of calcium

Questions 12–14 refer to the following graphs:

12. The slope of volume vs. pressure for a gas at constant temperature

13. The slope of pressure vs. temperature for a gas at constant volume

14. The slope of volume vs. temperature for a gas at constant pressure

Questions 15–18

(A) Least-reactive family of elements

(B) Alkali metals

(C) Halogen family of elements

(D) Noble gases

(E) Family whose oxides form acids in water

15. The elements that most actively react with water to release hydrogen

16. The elements least likely to become involved in chemical reactions

17. Family that contains elements in the colored gaseous state, in the liquid state, and with metallic properties

18. Group of nonmetallic elements containing N and P

Questions 19–23

(A) 1s

(B) 2s

(C) 3s

(D) 3p

(E) 3d

19. Contains up to ten electrons

20. Contains one pair of electrons in the ground state of the lithium atom

21. Is exactly one-half filled in the ground state of the phosphorous atom

22. Contains the valence electrons in the ground state of the magnesium atom

23. Contains a filled orbital of electrons in the ground state of helium

Part B

ON THE ACTUAL CHEMISTRY TEST, THE FOLLOWING TYPE OF QUESTION MUST BE ANSWERED ON A SPECIAL SECTION (LABELED “CHEMISTRY”) AT THE LOWER LEFT-HAND CORNER OF YOUR ANSWER SHEET. THESE QUESTIONS WILL BE NUMBERED BEGINNING WITH 101 AND MUST BE ANSWERED ACCORDING TO THE FOLLOWING DIRECTIONS.

Directions: Every question below contains two statements, I in the left-hand column and II in the right-hand column. For each question, decide if statement I is true or false and if statement II is true or false and fill in the corresponding T or F ovals on your answer sheet. *Fill in oval CE only if statement II is a correct explanation of statement I.

Sample Answer Grid:

CHEMISTRY * Fill in oval CE only if II is a correct explanation of I.

 

I

 

II

101.

The structure of SO3 is shown by using more than one
structural formula

BECAUSE

 

SO3 is very unstable and resonates between these possible structures.

102.

When the G of a reaction at a given temperature is negative, the reaction occurs spontaneously

BECAUSE

 

when G is negative, H is also negative.

103.

One mole of CO2 has a greater mass than 1 mole of H2O

BECAUSE

 

the molecular mass of CO2 is greater than the molecular mass of H2O.

104.

Hydrosulfuric acid is often used in qualitative tests

BECAUSE

 

H2S(aq) reacts with many metallic ions to give colored precipitates.

105.

Crystals of sodium chloride go into solution in water as ions

BECAUSE

 

the sodium ion has a 1+ charge and the chloride ion has a 1− charge and they are hydrated by the water molecules.

106.

If some phosphoric acid, H3PO4, is added to the equilibrium mixture represented by the equation H3PO4 + H2O ↔ PO43−
+ H3O+, the concentration of H3O+ decreases

BECAUSE

 

the equilibrium constant of a reaction changes as the concentration of the reactants changes

107.

The Hreaction of a particular reaction can be arrived at by the summation of the Hreaction values of two or more reactions that, added together, give the Hreaction of the particular reaction

BECAUSE

 

Hess’s Law conforms to the First Law of Thermodynamics, which states that the total energy of the universe is a constant.

108.

In a reaction that has both a forward and a reverse reaction,
A + B  AB, when only A and B are introduced into a reacting vessel, the forward reaction rate is the highest at the beginning and begins to decrease from that point until equilibrium is reached

BECAUSE

 

the reverse reaction does not begin until equilibrium is reached.

109.

At equilibrium, the forward reaction and reverse reaction stop

BECAUSE

 

at equilibrium, the reactants and products have reached the equilibrium concentrations.

110.

The hydrid orbital form of carbon in acetylene is believed to be the sp form

BECAUSE

 

C2H2 is a linear compound with a triple bond between the carbons.

111.

The weakest of the bonds between molecules are coordinate covalent bonds

BECAUSE

 

coordinate covalent bonds represent the weak attractive force of the electrons of one molecule for the positively charged nucleus of another.

112.

A saturated solution is not necessarily concentrated

BECAUSE

 

dilute and concentrated are terms that relate only to the relative amount of solute dissolved in the solvent.

113.

Lithium is the most active metal in the first group of the Periodic Table

BECAUSE

 

lithium has only one electron in the outer energy level.

114.

The anions migrate to the cathode in an electrolytic cell

BECAUSE

 

positively charged ions are attracted to the negatively charged cathode.

115.

The atomic number of a neutral atom that has a mass of 39
and has 19 electrons is 19

BECAUSE

 

the number of protons in a neutral atom is equal to the number of electrons.

116.

For an element with an atomic number of 17, the most probable oxidation number is +1

BECAUSE

 

the outer energy level of the halogen family has a tendency to add one electron to itself.

Part C

Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case and then fill in the corresponding oval on the answer sheet.

24. All of the following involve a chemical change EXCEPT

(A) the formation of HCl from Hand Cl 2

(B) the color change when NO is exposed to air

(C) the formation of steam from burning Hand O2

(D) the solidification of vegetable oil at low temperatures

(E) the odor of NHwhen NH4Cl is rubbed together with Ca(OH)2 powder

25. When most fuels burn, the products include carbon dioxide and

(A) hydrocarbons

(B) hydrogen

(C) water

(D) hydroxide

(E) hydrogen peroxide

26. In the metric system, the prefix kilo- means

(A) 100

(B) 10−1

(C) 10−2

(D) 102

(E) 103

27. How many atoms are in 1 mole of water?

(A) 3

(B) 54

(C) 6.02 × 1023

(D) 2(6.02 × 1023)

(E) 3(6.02 × 1023)

28. Which of the following elements normally exist as monoatomic molecules?

(A) Cl

(B) H

(C) O

(D) N

(E) He

29. The shape of a PClmolecule is described as

(A) bent

(B) trigonal planar

(C) linear

(D) trigonal pyramidal

(E) tetrahedral

30. The complete loss of an electron of one atom to another atom with the consequent formation of electrostatic charges is referred to as

(A) a covalent bond

(B) a polar covalent bond

(C) an ionic bond

(D) a coordinate covalent bond

(E) a pi bond between orbitals

31. In the electrolysis of water, the cathode reduction reaction is

(A) 2H2O(l) + 2e → H2(g) + 2OH + O2(g)

(B) 2H2O(l) → O2(g) + 2H+ + 2e

(C) 2OH + 2e → O2(g) + H2(g)

(D) 2H+ + 2e → H2(g)

(E) 2H2O(l) + 4e → O2(g) + 2H2(g)

32. Which of the following radiation emissions has no mass?

(A) Alpha particle

(B) Beta particle

(C) Proton

(D) Neutron

(E) Gamma ray

33. If a radioactive element with a half-life of 100 years is found to have transmutated so that only 25% of the original sample remains, what is the age, in years, of the sample?

(A) 25

(B) 50

(C) 100

(D) 200

(E) 400

34. What is the pH of an acetic acid solution if the [H3O+] = 1 × 10−4 mole/liter?

(A) 1

(B) 2

(C) 3

(D) 4

(E) 5

35. The polarity of water is useful in explaining which of the following?

  I. The solution process

 II. The ionization process

III. The high conductivity of distilled water

(A) I only

(B) II only

(C) I and II only

(D) II and III only

(E) I, II, and III

36. When sulfur dioxide is bubbled through water, the solution will contain

(A) sulfurous acid

(B) sulfuric acid

(C) hyposulfuric acid

(D) persulfuric acid

(E) anhydrous sulfuric acid

37. Four grams of hydrogen gas at STP contain

(A) 6.02 × 1023 atoms

(B) 12.04 × 1023 atoms

(C) 12.04 × 1046 atoms

(D) 1.2 × 1023 molecules

(E) 12.04 × 1023 molecules

38. Analysis of a gas gave: C = 85.7% and H = 14.3%. If the formula mass of this gas is 42 atomic mass units, what are the empirical formula and the true formula?

(A) CH; C4H4

(B) CH2; C3H6

(C) CH3; C3H9

(D) C2H2; C3H6

(E) C2H4; C3H6

39. Which fraction would be used to correct a given volume of gas at 300K to its new volume when it is heated to 333K and the pressure is kept constant?

40. What would be the predicted freezing point of a solution that has 684 grams of sucrose (1 mol = 342 g) dissolved in 2,000 grams of water?

(A) -1.86°C or 271.14 K

(B) -0.93°C or 272.07 K

(C) -1.39°C or 271.61 K

(D) -2.48°C or 270.52 K

(E) -3.72°C or 269.28 K

41. What is the approximate pH of a 0.005 M solution of H2SO4?

(A) 1

(B) 2

(C) 5

(D) 9

(E) 13

42. How many grams of NaOH are needed to make 100 grams of a 5% solution?

(A) 2

(B) 5

(C) 20

(D) 40

(E) 95

43. For the Haber process: N+ 3H 2NH3 + heat (at equilibrium), which of the following statements concerning the reaction rate is/are true?

  I. The reaction to the right will increase when pressure is increased.

 II. The reaction to the right will decrease when the temperature is increased.

III. The reaction to the right will decrease when NHis removed from the chamber.

(A) I only

(B) II only

(C) I and II only

(D) II and III only

(E) I, II, and III

44. If you titrate 1.0M H2SOsolution against 50. milliliters of 1.0M NaOH solution, what volume of H2SO4, in milliliters, will be needed for neutralization?

(A) 10.

(B) 25.

(C) 40.

(D) 50.

(E) 100

45. How many grams of COcan be prepared from 150 grams of calcium carbonate reacting with an excess of hydrochloric acid solution?

(A) 11

(B) 22

(C) 33

(D) 44

(E) 66

Question 46 refers to the following diagram:

46. The diagram represents a setup that may be used to prepare and collect

(A) NH3

(B) NO

(C) H2

(D) SO3

(E) CO2

47. The lab setup shown above was used for the gravimetric analysis of the empirical formula of MgO. In synthesizing MgO from a Mg strip in the crucible, which of the following is NOT true?

(A) The initial strip of Mg should be cleaned.

(B) The lid of the crucible should fit tightly to exclude oxygen.

(C) The heating of the covered crucible should continue until the Mg is fully reacted.

(D) The crucible, lid, and the contents should be cooled to room temperature before measuring their mass.

(E) When the Mg appears to be fully reacted, the crucible lid should be partially removed and heating continued.

Questions 48–50 refer to the following experimental setup and data:

Recorded data:

Weight of U-tube................................ 20.36 g

Weight of U-tube and calcium chloride before................................................... 39.32 g

Weight of U-tube and calcium chloride after................................................... 57.32 g

Weight of boat and contents (copper oxide) before................................................... 30.23 g

Weight of boat and contents after................................................... 14.23 g

Weight of boat...................................................5.00 g

48. What is the reason for the first CaCldrying tube?

(A) Generate water

(B) Absorb hydrogen

(C) Absorb water that evaporates from the flask

(D) Decompose the water from the flask

(E) Act as a catalyst for the combination of hydrogen and oxygen

49. What conclusion can be derived from the data collected?

(A) Oxygen was lost from the CaCl2.

(B) Oxygen was generated in the U-tube.

(C) Water was formed from the reaction.

(D) Hydrogen was absorbed by the CaCl2.

(E) CuO was formed in the decomposition.

50. What is the ratio of the mass of water formed to the mass of hydrogen used in the formation of water?

(A) 1 : 8

(B) 1 : 9

(C) 8 : 1

(D) 9 : 1

(E) 8 : 9

51. What is the mass, in grams, of 1 mole of KAl(SO4)2 · 12H2O?

(A) 132

(B) 180

(C) 394

(D) 474

(E) 516

52. What mass of aluminum will be completely oxidized by 2 moles of oxygen at STP?

(A) 18 g

(B) 37.8 g

(C) 50.4 g

(D) 72.0 g

(E) 100.8 g

53. In general, when metal oxides react with water, they form solutions that are

(A) acidic

(B) basic

(C) neutral

(D) unstable

(E) colored

Questions 54–56 refer to the following diagram:

54. The oxidation reaction will occur at

(A) A

(B) B

(C) C

(D) D

(E) E

55. The apparatus at is called the

(A) anode

(B) cathode

(C) salt bridge

(D) ion bridge

(E) osmotic bridge

56. The standard potentials of the metals are:

Zn2+ + 2e → Zn0       E0 = −0.76 volt

Cu0 → Cu2+ + 2e      E0 = −0.34 volt

What will be the voltmeter reading for this reaction?

(A) +1.10

(B) −1.10

(C) +0.42

(D) −0.42

(E) −1.52

________________________

57. How many liters of oxygen (STP) can be prepared from the decomposition of 212 grams of sodium chlorate (1 mol = 106 g)?

(A) 11.2

(B) 22.4

(C) 44.8

(D) 67.2

(E) 78.4

58. In this equation: Al(OH)+ H2SO→ Al2(SO4)+ H2O, the whole-number coefficients of the balanced equation are

(A) 1, 3, 1, 2

(B) 2, 3, 2, 6

(C) 2, 3, 1, 6

(D) 2, 6, 1, 3

(E) 1, 3, 1, 6

59. What is Hreaction for the decomposition of 1 mole of sodium chlorate? (Hf0 values: NaClO3(s) = −85.7 kcal/mol, NaCl(s) = −98.2 kcal/mol, O2(g) = 0 kcal/mol)

(A) −183.9 kcal

(B) −91.9 kcal

(C) +45.3 kcal

(D) +22.5 kcal

(E) −12.5 kcal

60. Isotopes of an element are related because which of the following is (are) the same in these isotopes?

  I. Atomic mass

 II. Atomic number

III. Arrangement of orbital electrons

(A) I only

(B) II only

(C) I and II only

(D) II and III only

(E) I, II, and III

61. In the reaction of zinc with dilute HCl to form H2, which of the following will increase the reaction rate?

  I. Increasing the temperature

 II. Increasing the exposed surface of zinc

III. Using a more concentrated solution of HCl

(A) I only

(B) II only

(C) I and III only

(D) II and III only

(E) I, II, and III

62. The laboratory setup shown above can be used to prepare a

(A) gas lighter than air and soluble in water

(B) gas heavier than air and soluble in water

(C) gas soluble in water that reacts with water

(D) gas insoluble in water

(E) gas that reacts with water

63. In this reaction: CaCO+ 2HCl → CaCl2 + H2O + CO2. If 4.0 moles of HCl are available to the reaction with an unlimited supply of CaCO3, how many moles of CO2 can be produced at STP?

(A) 1.0

(B) 1.5

(C) 2.0

(D) 2.5

(E) 3.0

64. A saturated solution of BaSOat 25°C contains 3.9 × 10−5 mole/liter of Ba2+ ions. What is the Ksp of this salt?

(A) 3.9 × 10−5

(B) 3.9 × 10−6

(C) 2.1 × 10−7

(D) 1.5 × 10−8

(E) 1.5 × 10−9

65. If 0.1 mole of K2SOwas added to the solution in question 64, what would happen to the Ba2+ concentration?

(A) It would increase.

(B) It would decrease.

(C) It would remain the same.

(D) It would first increase, then decrease.

(E) It would first decrease, then increase.

66. Which of the following will definitely cause the volume of a gas to increase?

  I. Decreasing the pressure with the temperature held constant.

 II. Increasing the pressure with a temperature decrease.

III. Increasing the temperature with a pressure increase.

(A) I only

(B) II only

(C) I and III only

(D) II and III only

(E) I, II, and III

67. The number of oxygen atoms in 0.50 mole of Al2(CO3)is

(A) 4.5 × 1023

(B) 9.0 × 1023

(C) 3.6 × 1024

(D) 2.7 × 1024

(E) 5.4 × 1024

Question 68 refers to a solution of 1 M acid, HA, with K= 1 × 10−6.

68. What is the H3O+ concentration? (Assume [HA] = 1, [H3O+] = x, [A] = x.)

(A) 1 × 10−5

(B) 1 × 10−4

(C) 1 × 10−2

(D) 1 × 10−3

(E) 0.9 × 10−3

________________________

69. What is the percent dissociation of acetic acid in a 0.1 M solution if the [H3O+] is 1 × 10−3 mole/liter?

(A) 0.01%

(B) 0.1%

(C) 1.0%

(D) 1.5%

(E) 2.0%

If you finish before one hour is up, you may go back to check your work or complete unanswered questions.

Answer Key

P  R  A  C  T  I  C  E   T  E  S  T   2

1. E

14. C

104. T, T, CE

2. B

15. B

105. T, T, CE

3. D

16. D

106. F,F

4. A

17. C

107. T, T, CE

5. B

18. E

108. T, F

6. C

19. E

109. F, T

7. A

20. A

110. T, T, CE

8. B

21. D

111. F, F

9. D

22. C

112. T, T, CE

10. C

23. A

113. F, T

11. E

101. T, F

114. F, T

12. E

102. T, F

115. T, T, CE

13. A

103. T, T, CE

116. F, T

24. D

39. E

54. A

25. C

40. A

55. C

26. E

41. B

56. A

27. E

42. B

57. D

28. E

43. C

58. C

29. D

44. B

59. E

30. C

45. E

60. D

31. D

46. E

61. E

32. E

47. B

62. D

33. D

48. C

63. C

34. D

49. C

64. E

35. C

50. D

65. B

36. A

51. D

66. A

37. E

52. D

67. D

38. B

53. B

68. D

   

69. C

ANSWERS EXPLAINED

1. (E) A phase diagram shows that all three states can exist at the triple point.

2. (B) The combining of nuclei is called nuclear fusion.

3. (D) According to Graham’s Law of Gaseous Diffusion (or Effusion), the rate of diffusion is inversely proportional to the square root of the mole cular weight.

      Then

4. (A) The Law of Definite Composition states that, when compounds form, they always form in the same ratio by mass. Water, for instance, always forms in a ratio of 1 : 8 of hydrogen to oxygen by mass. For nitrogen monoxide (NO) and nitrogen dioxide (NO2) the difference in molecular mass is one atomic mass of oxygen.

5. (B) The first step is the for C + O→ CO. It releases -110.5 kJ of 12 heat. This is written as -110.5 kJ because it is exothermic.

6. (C) This is the second step on the diagram. It releases -283.0 kJ of heat.

7. (A) To arrive at the H, take the total drop (−393.5 kJ) or add these reactions:

8. (B) Potassium and chlorine have a large enough difference in their electronegativities to form ionic bonds. The respective positions of these two elements in the periodic chart also are indicative of the large difference in their electronegativity values.

9. (D) Two atoms of an element that forms a diatomic molecule always have a nonpolar covalent bond between them since the electron attraction or electronegativity of the two atoms is the same.

10. (C) Electronegativity differences between 0.5 and 1.7 are usually indicative of polar covalent bonding. COis an interesting example of a nonpolar molecule with polar covalent bonds since the bonds are symmetrical in the molecule.

11. (E) Calcium is a metal and forms a metallic bond between atoms.

12. (E) This graph shows the volume decreasing as the pressure is increased and the temperature is held constant. It is an example of Charles’s Law (V/T = k).

13. (A) This graph shows the pressure increasing as the temperature is increased and the volume is held constant. It is an example of Gay-Lussac’s Law (P/T = k).

14. (C) This graph shows the volume increasing as the temperature is increased and the pressure is held constant. It is an example of Boyle’s Law (PV = k).

15. (B) The alkali metals react with water to form hydroxides and release hydrogen. A typical reaction is:

2Na(s) + 2H2O() → 2NaOH(aq) + H2(g)

16. (D) The noble gases are the least reactive because of their completed outer orbital.

17. (C) The halogen family contains the colored gases fluorine and chlorine at room temperatures, the reddish liquid bromine, and metallic-like purple iodine.

18. (E) These nonmetals, when they are oxides, react as acidic anhydrides with water to form acid solutions.

19. (E) The five 3orbitals can contain a total of ten electrons.

20. (A) The 1orbital is filled with two electrons in the lithium atom.

21. (D) The phosphorous atom has a half-filled 3orbital level.

22. (C) The 3orbital contains the valence electrons of magnesium.

23. (A) The helium atom has a filled 1orbital.

101. (T, F) Sulfur trioxide is shown by three structural formulas because each bond is “hybrid” of a single and double bond. Resonance in chemistry does not mean that the bonds resonate between the structures shown in the structural drawing.

102. (T, F) When is negative in the Gibbs equation, the reaction is spontaneous. However, the total equation determines this, not just the H. The Gibbs equation is:

G = H − T S.

103. (T, T, CE) One mole of each of the gases contains 6.02 × 1023 molecules, but their molecular masses are different. COis found by adding one C = 12 and two O = 32, or a total of 44 amu. The H2O, however, adds up to two H = 2 plus one O = 16, or a total of 18 amu. Thus it is true that 1 mol of COat 44 g/mol is heavier than 1 mol of H2O at 18 g/mol.

104. (T, T, CE) Hydrosulfuric acid is a weak acid but is used in qualitative tests because of the distinctly colored precipitates of sulfides that it forms with many metallic ions.

105. (T, T, CE) Sodium chloride is an ionic crystal, not a molecule, and its ions are hydrated by the polar water molecules.

106. (F,F) The addition of more H3PO4 causes the equilibrium to shift to the right and increase the concentration of H3O+ ions until equilibrium is restored. Therefore the first statement is false. The second is also false since the equilibrium constant remains the same at a given temperature.

107. (T, T, CE) The statement is true, and the reason is also true and explains the statement.

108. (T, F) The statement is true, but not the reason. In an equilibrium reaction, concentrations can be shown to progress like this:

until equilibrium is reached. Then the concentrations stabilize.

109. (F, T) The forward and reverse reactions are occurring at equal rates when equilibrium is reached. The reactions do not stop. The concentrations remain the same at this point.

110. (T, T, CE) Since acetylene is known to be a linear molecule with a triple bond between the two carbons, the sp orbitals along the central axis with the hydrogens bonded on either end fit the experimental evidence.

111. (F, F) The weakest bonds between molecules are van der Waals forces, not coordinate covalent bonds.

112. (T, T, CE) The terms dilute and concentrated merely indicate a relatively large amount of solvent and a small amount of solvent, respectively. You can have a dilute saturated solution if the solute is only slightly soluble.

113. (F, T) Cs, not Li, is the most active Group I metal because Cs has (a) the largest atomic radius, thus making it easier to lose its outer energy level electron, and (b) the intermediate electrons help screen the positive attraction of the nucleus, also increasing the ease with which the outer electron is lost.

114. (F, T) The cations are positively charged ions and migrate to the cathode, while the anions are negatively charged and migrate to the anode.

115. (T, T, CE) There are as many electrons as there are protons in a neutral atom, and the atomic number represents the number of each.

116. (F, T) The first two principal energy levels fill up at 2 and 8 electrons, respectively. That leaves 7 electrons to fill the 3and 3orbitals like this: 3s2, 3p5. With only one electron missing in the 3orbitals, the most likely oxidation number is −1.

24. (D) The solidification of vegetable oil is merely a physical change, like the formation of ice from liquid water at lower temperatures. All the other choices involve actual recombinations of atoms and thus are chemical changes.

25. (C) Water is formed because most common fuels contain hydrogen in their structures.

26. (E) The other choices, in order, represent 1,  or deci-, or centi-, and 100 or hect-.

27. (E) One mole of any substance contains 6.02 × 1023 molecules. Since each water molecule is triatomic, there would be 3(6.02 × 1023) atoms present.

28. (E) The noble gases are all monoatomic because of their complete outer energy levels. A rule to help you remember diatomic gases is: Gases ending in -gen or -ine usually form diatomic molecules.

29. (D) By both the VSEPR (valence shell electron pair repulsion) method and the orbital structure method, the PClmolecule is trigonal pyramidal:

30. (C) The complete loss and gain of electrons is an ionic bond. All other bonds indicated are “sharing of electrons” type bonds or some form of covalent bonding.

31. (D) The cathode reaction releases only Hgas. This half-reaction is as given in (D).

32. (E) The beta particle is a high-speed electron and has the smallest mass of the first four choices. However, gamma rays are electromagnetic waves. They have no mass.

33. (D) If 25% of the sample now remains, then 100 years ago 50% would be present. If you go back another 100 years, the sample would contain 100% of the radioactive element. Therefore, the sample is 100 + 100 = 200 years old.

34. (D) pH = −log[H3O+] = −log[1 × 10−4] = −(−4) = 4.

35. (C) Only I and II are true. Distilled water does not significantly conduct an electric current. The polarity of the water molecule is helpful in ionization and in causing substances to go into solution.

36. (A) SOis the acid anhydride of H2SOor sulfurous acid. H2O + SO→ H2SO3.

37. (E) Four grams of hydrogen gas at STP represent 2 mol of hydrogen since 2 g is the gram-molecular mass of hydrogen. Each mole of a gas contains 6.02 × 1023 molecules, so 2 mol contains 2 × 6.02 × 1023 or 12.04 × 1023 molecules.

38. (B) To solve percent composition problems, first divide the % given by the atomic mass:

Then divide by the smallest quotient to get small whole numbers:

The empirical formula is CH2. Since the molecular mass is 42 and the empirical formula has a molecular mass of 14, the true formula must be 3 times the empirical formula, or C3H6.

39. (E) Because the temperature (in kelvins) increases from 303 K to 333 K, the volume of the gas should increase with pressure held constant. The correct fraction is .

40. (A) One mole of dissolved substance (which does not ionize) causes a 1.86°C drop in the freezing point of a 1 molal solution. Since 2,000 g of water were used, the solution has  or 2 mol in 2,000 g of water. Then

The freezing point is depressed 1 × −1.86° = −1.86°C or 271.14 K.

41. (B) The pH is −log[H+]. A 0.005 molar solution of H2SOionizes in a dilute solution to release two H+ ions per molecule of H2SO4. Therefore the molar concentration of H+ ion is 2 × 0.005 mol/L or 0.010 mol/L. Substituting this in the formula, you have:

pH = −log[0.01]= −log[1 × 10−2]

The log of a number is the exponent to which the base 10 is raised to express that number in exponential form:

− log[1 × 10−2]= −[−2]= 2

42. (B) If the solution is to be 5% sodium hydroxide, then 5% of 100 g is 5 g. Percent is always by mass unless otherwise specified.

43. (C) Because this equation is exothermic, higher temperatures will decrease the reaction to the right and increase the reaction to the left, so II is true.

Also, I is true because with an increase of pressure the reaction will try to relieve that pressure by going in the direction that has the least volume: in this reaction, to the right. Statement III is false because removing product in this reaction would increase the forward reaction. Statements I and II are true.

44. (B) The reaction is:

1 mol acid = (mol) of base

Since

molarity × volume (L) = moles,

then

MaVa = MbVb   
  (1.0 M)(x L) = (1 M)(0.05 L)   

        x L = (0.05 L)   
                     x L = 0.025 L or 25.mL   

45. (E) The reaction is:

150 g

CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)

The gram-molecular mass of calcium is 100 g. Then 150 g =  or 1.5 mol of calcium carbonate. According to the equation, 1 mol of CaCOyields 1 mol of carbon dioxide, so 1.5 mol of CaCOyields 1.5 mol of CO2.

The gram-molecular mass of CO= 44 g:

1.5 mol of CO= 1.5 × 44 g = 66 g CO2

46. (E) The other choices are wrong because:

(A) is lighter than air

(B) reacts with air

(C) is lighter than air

(D) needs heat to be evolved

47. (B) The Mg needs oxygen to form MgO; so the lid cannot be tightly sealed. Oxygen is needed for the Mg to oxidize to MgO. All other choices are true.

48. (C) To ensure that all the water vapor collected in the U-tube comes from the reaction, the first drying tube is placed in the path of the hydrogen to absorb any evaporated water.

49. (C) Calcium chloride is deliquescent, and its weight gain of water indicates that water was formed from the reaction.

50. 
The ratio of mass of water to mass of hydrogen is 18 : 2 or 9 : 1.

51. (D) 1 K = 39, 1Al = 27, 2(SO4) = 2(32 + 16 × 4) = 192, and 12H2O = 12(2 + 16) = 216. This totals 474 g.

52. (D) 
Or, using the mole method: 44.8 L = 2 mol



This shows that:



Since molar mass of Al = 27/mol

53. (B) Metal oxides are generally basic anhydrides.

54. (A) Since A is the anode, the oxidation (or loss of electrons) will occur on this pole.

55. (C) “Salt bridge” is the correct terminology.

56. (A) Zn → Zn2+ + e      E ° = +0.76 V 

Cu2+ + 2e  → Cu °E ° = +0.34 V 

                        Total is = +1.10 V 

(Notice that the Zn is being oxidized and the Cu2+ is being reduced.)
Voltmeter will read +1.10 V.

57. (D) 
      
Equation shows 
2 mol → 3 mol O2 
3 mol × 22.4 L/mol = 67.2 L

58. (C) The balanced equation has the coefficients 2, 3, 1, and 6: 2Al(OH)+ 3H2SO4 → Al2(SO4)+ 6H2O.

59. (E) The reaction is NaClO3(s) → NaCl(s) + O2(g).
Hreaction = Hf (products) − Hf (reactants)
Hreaction = (−98.2 + 0) − (−85.7)
Hreaction = −12.5 kcal

60. (D) II and III are identical; isotopes differ only in the number of neutrons in the nucleus and this affects the atomic mass only.

61. (E) I, II, and III will increase the rate of this reaction. Each of them causes the rate of this reaction to increase.

62. (D) This setup depends on water displacement of an insoluble gas.

63. (C) The coefficients give the molar relations, so 2.0 mol of HCl give off 1.0 mol of CO2. Given 4.0 mol of HCl, you have

64. (E) Ksp = [Ba2+] [SO42−] since [Ba2+] is given as [3.9 × 10−5], and the equation BaSO4 → Ba2+ + SO42− shows there will be as many SO42− ions as Ba2+ ions, then both [Ba2+] and [SO42− will equal 3.9 × 10−5. So,
Ksp = [3.9 × 10−5][3.9 × 10−5
Ksp = 1.5 × 10−9

65. (B) The introduction of the “common ion” SO42− at 0.1 molar forces the equilibrium to shift to the left and reduce the Ba2+ concentration.

66. (A) According to the gas laws, only I will cause an increase in the volume of a confined gas.

67. (D) In 1 mol of Al2(CO3)3, nine oxygens (three carbonates with three oxygen atoms each) are in each molecule, or 9 mol of O atoms are in 1 mol of Al2(CO3)3. Because only 0.50 mol is given, there are (9) or 4.5 mol of O atoms. In 4.5 mol of oxygen, there are

    27.0 × 1023 atoms or 2.7 × 1024 atoms.

68. (D) When HA ionizes, it forms equal amounts of H+ and A ions, but these amounts are very small because the Kis very small. Kcan be expressed as [H+] [A]/[HA]. Because you are told to assume [HA] = 1, you have:

69. (C) Percent dissociation =

CALCULATING YOUR SCORE

Your score on Practice Test 2 can now be computed manually. The actual test is scored by machine, but the same method is used to arrive at the raw score. You get one point for each correct answer. For each wrong answer, you lose one-fourth of a point. Questions that you omit or that have more than one answer are not counted. On your answer sheet mark all correct answers with a “C” and all incorrect answers with an “X”.

Determining Your Raw Test Score

Total the number of correct answers you have recorded on your answer sheet. It should be the same as the total of all the numbers you place in the block in the lower left corner of each area of the Subject Area summary in the next section.

  A. Enter the total number of correct answers here: ________ 
Now count the number of wrong answers you recorded on your answer sheet.

  B. Enter the total number of wrong answers here: ________ 
Multiply the number of wrong answers in B by 0.25.

  C. Enter that product here: ________ 
Subtract the result in C from the total number of right answers in A.

  D. Enter the result of your subtraction here: ________

  E. Round the result in D to the nearest whole number: ________.
This is your raw test score.

Conversion of Raw Scores to Scaled Scores

Your raw score is converted by the College Board into a scaled score. The College Board scores range from 200 to 800. This conversion is done to ensure that a score earned on any edition of a particular SAT Subject Test in Chemistry is comparable to the same scaled score earned on any other edition of the same test. Because some editions of the tests may be slightly easier or more difficult than others, scaled scores are adjusted so that they indicate the same level of performance regardless of the edition of the test taken and the ability of the group that takes it. Consequently, a specific raw score on one edition of a particular test will not necessarily translate to the same scaled score on another edition of the same test.

Because the practice tests in this book have no large population of scores with which they can be scaled, scaled scores cannot be determined.

Results from previous SAT Chemistry tests appear to indicate that the conversion of raw scores to scaled scores GENERALLY follows this pattern:

Note that this scale provides only a general idea of what a raw score may translate into on a scaled score range of 800–200. Scaling on every test is usually slightly different. Some students who had taken the SAT Subject Test in Chemistry after using this book had reported that they have scored slightly higher on the SAT test than on the practice tests in this book. They all reported that preparing well for the test paid off in a better score!

DIAGNOSING YOUR NEEDS

After taking Practice Test 2, check your answers against the correct ones. Then fill in the chart below.

In the space under each question number, place a check if you answered that question correctly.

EXAMPLE:

If your answer to question 5 was correct, place a check in the appropriate box.

Next, total the check marks for each section and insert the number in the designated block. Now do the arithmetic indicated and insert your percent for each area.

*The subject areas have been expanded to identify specific areas in the text.

* The subject areas have been expanded to identify specific areas in the text.

*The subject areas have been expanded to identify specific areas in the text.

* The subject areas have been expanded to identify specific areas in the text.

Answer Sheet

P  R  A  C  T  I  C  E   T  E  S  T   3

Determine the correct answer for each question. Then, using a No. 2 pencil, blacken completely the oval containing the letter of your choice.