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ACS Practice Test 1
Acids & Bases:
- All are examples of Lewis acid–base reactions except
(A) Cu2+ (aq) + 4NH 3 (aq) →← [Cu(NH 3 ) 4 ]2+ (aq)
(B) HCl (g) + NH 3 (g) → NH 4 Cl (s)
(C) H+ (aq) + OH– (aq) →← H 2 O (l)
(D) 2Na (s) + Cl 2 (g) → 2NaCl (s)
- According to the Lewis definition, an acid is a species (A) having a hydrogen ion. (B) donating a pair of electrons. (C) accepting a pair of electrons. (D) accepting a hydrogen ion.
- All are potential Lewis bases except (A) NH 3 (B) H 2 O (C) CH 4 (D) CN–
- Which hydrated metal ion is most acidic under conditions of equal molar concentration in water? (A) Al 3+^ (B) Ba 2+^ (C) K+^ (D) Zn2+^ (E) Ag +
- Which element in Group 5A forms the most basic oxide? (A) N (B) P (C) As (D) Sb (E) Bi
Atomic Structure:
- In what respect does an atom of magnesium differ from a magnesium ion (Mg2+)? (A)The ion has a more stable electronic arrangement than the atom. (B)The positive charge on the nucleus of the ion is two units greater than the nuclear charge on the atom. (C)The ion has two more protons than the atom. (D)The ion will react more readily with free Cl 2. (E)The ion has two more planetary electrons than the atom.
- A certain atom has the symbol 148 73 Px. What does this symbol tell about an atom of the element? (A) It has 148 electrons. (B) It has a valence of 4. (C) It has 221 protons in the nucleus. (D) It has 75 neutrons in the nucleus. (E) Its atomic mass is 73 u.
- The atomic mass of an element is 32.07 u and its atomic number is 16. The number of protons contained in the nucleus of an atom of this element is (A) 16 (B) 31 (C) 32 (D) 48
- The atomic mass of an element is 32.07 u and its atomic number is 16. The element forms a simple ion. The ion will most likely have a charge of (A) 1– (B) 2– (C) 3+ (D) 1+
- The nucleus of which atom contains seven neutrons?
Atom A n = 1 n = 2 n = 3 M = 24, Z = 12 2 e -^8 e -^2 e -
Atom B n = 1 n = 2 n = 3 M = 15, Z = 7 2 e -^5 e -
Atom C n = 1 n = 2 n = 3 M = 17, Z = 10 2 e -^8 e -
Atom D n = 1 n = 2 n = 3 M = 7, Z = 3 2 e -^1 e -
Atom E n = 1 n = 2 n = 3 M = 34, Z = 17 2 e -^8 e -^7 e - (A) A (B) B (C) C (D) D (E) E
Bonding:
- In which pair of compounds should the first member be more covalent than the second member? (A) TlCl, TlCl 3 (B) SnI 4 , SnF 4 (C) LiF, BF 3 (D) SnF 4 , CF 4
- Which is the most complete and best description of a covalent bond? (A)a system of two nuclei with a pair of electrons located exactly midway between both nuclei (B)the attractive force between two atoms of opposite charge (C)a donor bond in which one atom donates an unshared pair to the other (D)a system of two nuclei where each atom donates one electron to the other atom, thus forming a bond
- Which pair of elements is most likely to react to form a covalently bonded species? (A) P and O (B) Ca and O (C) K and S (D) Zn and C
- Which chloride should exhibit the most covalent type of bond? (A) NaCl (B) KCl (C) CaCl 2 (D) BaCl 2 (E) BeCl (^2)
- The compound of which two elements is most likely to involve covalent bonding?
Electronegativities of Unknown Elements Q 0.9 X 3. R 1.0 Z 4. T 2.
(A) Q and Z (B) R and T (C) T and X (D) R and X (E) R and Z
Electrochemistry:
- Chromium metal can be plated from an acidic solution of CrO 3.
CrO 3 (aq) + 6H+ (aq) + 6 e –^ → Cr (s) + 3H 2 O How many grams of chromium will be plated by the passage of 19,300 C (coulombs)? (A) 10.4 (B) 5.19 (C) 1.73 (D) 0.
- The reaction for the formation of ammonia by direct combination is
N 2 + 3H 2 →← 2NH 3 ∆ H = –92 kJ Which operation will increase the yield of ammonia in the equilibrium mixture? (A) doubling the concentration of hydrogen (B) reducing the total pressure (C) raising the temperature (D) increasing the reaction time (E) adding a catalyst
- Chemical equilibrium is the result of (A) a decrease in speed of reaction. (B) the unavailability of one of the reactants. (C) a stoppage of further reaction. (D) opposing reactions attaining equal speeds. (E) formation of products equal in mass to the reactants.
Formulas & Equations:
- Complete and balance the equation for the combustion of ZnS in excess oxygen
? ZnS +? O 2 →? ZnO +? Use no fractional coefficients. The number of moles and the formula of the product containing S are (A) 2S (B) S 8 (C) SO 2 (D) 2SO 2 (E) SO 3
- Balance the equation for the reaction, using no fractional coefficients.
? P +? HNO 3 +? H 2 O →? H 3 PO 4 +? NO
The ratio of the moles of oxidizing agent to moles of reducing agent in the balanced equation is (A) 5 to 2. (B) 5 to 3. (C) 3 to 5. (D) 2 to 5. (E) 1 to l.
- Balance the equation for the reaction, using no fractional coefficients.
? Cr 2 O 3 +? KOH +? O 2 →? K 2 CrO 4 +? H 2 O The coefficient of KOH in the balanced equation is (A) 2 (B) 4 (C) 6 (D) 8 (E) 10
- Why is the equation incorrect? Mg 3 + N 2 → Mg 3 N 2 (A) Some of the subscripts are incorrectly used. (B) The equation is not balanced. (C) The valence of the nitride ion is incorrect. (D) The valance of the magnesium ion is incorrect. (E) The coefficient of N 2 is incorrect.
- A lithium carbide (Li x C y ) reacts with water as follows:
Li x C y + H 2 O → LiOH + C 2 H 2 (unbalanced) What is the simplest formula of the carbide? (A) LiC (B) Li 2 C (C) LiC 2 (D) Li 3 C 4
Gases:
- In which gas are the forces between molecules strongest? (A) Ne (B) CH 4 (C) O 2 (D) H 2 O
- The density of a gas is 1.96 g·L –1^ at 1.00 atm and 0 °C. What is the density of this gas at 0.855 atm and 25.0 C? (A)0.00276 g·L–1^ (B)0.651 g·L–1^ (C)1.54 g·L–1^ (D)1.82 g·L–
- A 1200 mL sample of helium gas is at a pressure of 350 mmHg and a temperature of 300 K. What volume will this gas sample occupy if the pressure is increased to 700 mmHg and the temperature is increased to 400 K? (A) 450 mL (B) 800 mL (C) 1650 mL (D) 3200 mL
- The height of the mercury in the right arm open to atmospheric pressure (760 mmHg) is 100 mm and the height in the left arm is 120 mm.
120 mm (^) 100 mm
gas
What is the pressure of the gas in the bulb? (A)20 mmHg (B)640 mmHg (C)740 mmHg (D)780 mmHg
- A sample of nitrogen at pressure^ P^ is contained in a sealed syringe with a movable piston. If the volume of the sample were doubled and the absolute temperature tripled, the new pressure of the gas would be (A) 6.0 P (B) 5.0 P (C) 3.5 P (D) 1.5 P
Introductory Concepts:
- When equal volumes of 0.1 M solutions of HCl and NaOH are mixed, the total number of ions present will be approximately (A) twice as great as before mixing. (B) the same as before mixing. (C) half as great as before mixing. (D) 10 –7^ times as great as before mixing. (E) 10 –14^ times as great as before mixing.
- Oxygen and ozone have the formulas O 2 and O 3 respectively. They are (A) isomers. (B) isobars. (C) allotropes. (D) isotopes.
- Which instrument is directly used to determine the relative masses of atoms? (A) spectroscope (B)Geiger counter (C)mass spectrograph (D)microbalance (E)electron microscope
- An enclosed mixture has a mass of 12.69723±0.00003 g, and after a chemical change occurs the mixture has a mass of 12.69724±0.00003 g. These results show that (A)the law of conservation of matter is not always true. (B)the law of conservation of mass is not always true. (C)the mass of the enclosed mixture remains constant within the experimental error of the measurement. (D)the mass of the enclosed mixture does not change. (E)the mass of the enclosed mixture increased.
(D)Add an excess over the calculated amount of solute to hot water and cool to 20 °C, with stirring. (E)Neutralize a dilute solution of KOH with dilute HNO 3 and evaporate to the desired volume.
- Incandescent carbon particles cause a gas flame to be yellow. To obtain a hotter blue flame you should (A)open the air holes. (B)close the air holes. (C)open the needle valve at the base of the burner to increase the gas supply. (D)partly close the supply valve at the gas jet. (E)place a beaker of cold water over the flame to cool the flame.
- The electrical conductance of a solution of Ba(OH) 2 slowly decreases upon the addition of H 2 SO 4 to a minimum, and then slowly increases. The best experimental evidence for this is (A)The Ba(OH) 2 solution becomes more dilute since its volume is increased by adding the H 2 SO 4 solution. (B)Ions are removed from the solution by the formation of water and insoluble BaSO 4. (C)The inter-ionic attraction effect is increased by adding the H 2 SO 4. (D)An electric lamp placed in a circuit in series with the solution becomes dim as the H 2 SO 4 is added and then becomes bright again. (E)An indicator placed in the solution changes color.
Metals & Non-Metals:
- Heating zinc sulfide in air causes the formation of (A)Zn and S. (B)Zn and SO2. (C)ZnO and S (D)ZnO and SO 2. (E)Zn and SO 3.
- The electrical conductance of a solution of Ba(OH) 2 slowly decreases upon the addition of H 2 SO 4 to a minimum, and then slowly increases. The best theoretical explanation of this is (A)The Ba(OH) 2 solution becomes more dilute since its volume is increased by adding the H 2 SO 4 solution. (B)Ions are removed from the solution by the formation of water and insoluble BaSO 4. (C)The interionic attraction effect is increased by adding the H 2 SO 4. (D)An electric lamp placed in a circuit in series with the solution becomes dim as the H 2 SO 4 is added and then becomes bright again. (E)An indicator placed in the solution changes color.
- Which group of ions can exist together in water solution in moderate concentration? (A) Ba 2+, NO 3 –^ , K+, CO 3 2–^ (B) Ba 2+, Cl –^ , K+, SO 4 2– (C) K+, Cl –^ , Na +^ , NO 3 –^ (D) Ag +, NO 3 –^ , K+, Cl – (E) Na +, Pb 2+, Cl –^ , NO 3 –
- Which mixture will not yield hydrogen gas? (A) sodium and water (B) calcium and water (C) zinc and hydrochloric acid (D) zinc and concentrated nitric acid (E) steam and red hot iron
- When sodium hydroxide solution is added to magnesium sulfate solution, a white precipitate of magnesium hydroxide is obtained. When sodium hydroxide solution is added to an “unknown” solution, a white precipitate is obtained. To conclude that the unknown solution contains magnesium ion, it must be assumed that (A)NaOH is more soluble than Mg(OH) 2. (B)Na 2 SO 4 is soluble in water.
(C)Mg(OH) 2 is insoluble in water. (D)NaOH forms no white precipitate with any other ion except Mg 2+. (E)Zn2+, which forms white Zn(OH) 2 , is not present in the unknown.
Molecular Geometry:
- An sp hybridized central atom can be used to describe the bonding in (A) CH 4 (B) HCN (C) H 2 CO (D) OF (^2)
- Sulfur dioxide can be described by the structures:
: S : (^) O ::^ :O^ : O S : ::O :
This implies that (A)the two bonds in SO 2 are of equal length, and the electronic distribution in the two SO bonds is identical. (B)the single bond is longer than the double bond and the electronic distribution in the two SO bonds is different. (C)an electron pair in the SO 2 molecule alternates back and forth between the two sulfur–oxygen electron pairs so that the two different bonds seem to exchange positions. (D)the SO 2 molecule revolves so that the two different bonds seem to exchange positions.
- Which compound would be expected to have the largest dipole moment? (A)CO 2 (linear) (B)SO 2 (bent) (C)BF 3 (trigonal planar) (D)CF 4 (tetrahedral)
- Which is the largest bond angle? (A) angle O–S–O in SO 4 2– (B) angle Cl–C–Cl in HCCl 3 (C) angle F–Be–F in BeF 2 (D) angle H–O–H in H 2 O
- Which molecule is polar? (A) BF 3 (B) CO 2 (C) CF 4 (D) H 2 S
Oxidation & Reduction:
- Consider the reaction 2Fe3+ (aq) + 2I – (aq) → 2Fe 2+ (aq) + I 2 (aq) Which statement is true for the reaction? (A) Fe 3+^ is oxidized. (B) Fe3+^ increases in oxidation number. (C) Fe 3+^ is reduced. (D) I –^ is reduced.
- In the chemical reaction, Zn (s) + CuSO 4 (aq) → ZnSO 4 (aq) + Cu (s) , (A) metallic zinc is the reducing agent. (B) metallic zinc in reduced. (C) copper ion is oxidized. (D) sulfate ion is the oxidizing agent.
- In this reaction, which substance behaves as the oxidizing agent? Pb + PbO 2 + 2H 2 SO 4 → 2PbSO 4 + 2H 2 O (A) Pb (B) PbSO 4 (C) PbO 2 (D) H 2 SO 4
- In which group can each substance act as an oxidizing agent?
(A) Cl 2 , MnO 2 , Cu (B)Cl 2 , MnO 4 –^ , Cu 2+^ (C)Cl–, MnO4–, Cu+^ (D)Cl 2 , Mn, Cu 2+
0.0 0.2 0.4 0.6 0.8 1. mole fraction of A
A and B react exothermically to form a compound. A series of experiments is performed in which varying ratios of A to B are used, with a constant total number of moles, in each case. The observed temperature rise is plotted above. The simplest formula for the compound is probably (A) A 3 B 2 (B) A 2 B 3 (C) AB 2 (D) AB
- If a 17.0 g sample of impure nickel metal reacts under standard conditions with 25.0 L of CO to form 6.25 L of Ni(CO) 4 gas, what is the percentage of Ni in the metal sample? Ni (s) + 4CO (g) → Ni(CO) 4 (g) Molar Masses Ni 58.7 g·mol – Ni(CO) 4 171. g·mol – (A) 24.1% (B) 25.0% (C) 96.4% (D) 100%
Thermochemistry
- Which molecule has the greatest bond energy? (A) H—Br (B) H—F (C) H—At (D) H—Cl (E) H—I
- For which process is the entropy change per mole the largest at constant temperature? (A)H 2 O (l) → H 2 O (g) (B)H 2 O (s) → H 2 O (g) (C)H 2 O (s) → H 2 O (l) (D)H 2 O (l) → H 2 O (s)
- Under which conditions does nitrogen have the largest entropy per mole? (A) N 2 (s) at 50 K and l atm (B) N 2 (l) at 70 K and l atm (C) N 2 (g) at 80 K and 1 atm (D) N 2 (g) at 80 K and 0.5 atm
- In which process is entropy decreased? (A)dissolving sugar in water (B)expanding a gas (C)evaporating a liquid (D)freezing water
- Which reaction has the largest positive entropy change per mole of product formed?
(A) S (s) + 3F 2 (g) → SF 6 (g) (B) SO 2 (g) + Na 2 O (s) → Na 2 SO 3 (s)
(C) Fe 3+ (aq) + SCN– (aq) → FeSCN2+ (aq) (D) H 2 O (l) → H 2 O (g)
ACS Practice Test 1 Answer Key
Acids & Bases:
- D
- C
- C
- A
- E Atomic Structure:
- A
- D
- A
- B
- C Bonding:
- B
- D
- A
- E
- C Electrochemistry:
- C
- B
- C
- A
- B Equilibrium:
- D
- D
- C
- A
- D Formulas & Equations:
- D
- B
- D
- A
- A Gases:
- D
- C
- B
- C
- D Introductory Concepts:
- C
- C
- C
- C
- D
Kinetics:
- A
- C
- D
- C
- A Laboratory:
- C
- C
- D
- A
- D Metals & Nonmetals:
- D
- B
- C
- D
- D Molecular Geometry:
- B
- A
- B
- C
- D Oxidation & Reduction:
- C
- A
- C
- B
- D Periodic Properties:
- B
- A
- E
- A
- A Stoichiometry:
- D
- C
- B
- B
- C Thermochemistry:
- B
- B
- D
- D
- D
