981_2nd_Exam_981111
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) In the synthesis of ammonia gas from nitrogen and hydrogen,
N2 (g) + 3 H2 (g) 2 NH3 (g)
what is the maximum volume, in liters, of NH3 that can be formed from 15.0 L of H2?
A) 7.50 B) 30.0 C) 15.0 D) 22.5 E) 10.0
Answer: E
2) The heat capacity of a bomb calorimeter is found to be 5.68 kJ °C-1. When a 1.652 g sample of glucose,C6H12O6 , is burned in the calorimeter, the temperature of the calorimeter increases from 24.56°C to 29.10°C. Calculate the H for the following reaction:
C6H12O6 (s)
+
6 O2 (g) 6 CO2 (g)+
6 H2O (g) A) -25.8 kJB) -42.6 kJ C) 25.8 kJ D) -2.81 × 103 kJ
E) 15.6 kJ Answer: D
3) The correct equation for which the enthalpy change defines the standard enthalpy of formation for C2H5OH (l) is:
A) CH3CHO (l)
+
H2 (g) CH3CH2OH (l) B) CH2=CH2 (g)+
H2O (l) CH3CH2OH (l) C) 2 C (gr)+
6 H (g)+
O (g) C2H5OH (l)D) 2 C (gr)
+
3 H2 (g) + 12O2 (g) C2H5OH (l) E) 4 C (gr)
+
6 H2 (g)+
O2 (g) 2 CH3CH2OH (l) Answer: D4) A 258-mL sample of MEK, an industrial solvent, is found to have a mass of 0.599 g at 0.988 atm and 100°C.
What is the molar mass of MEK?
A) 58.0 B) 72.0 C) 88.0 D) 98.0 E) 122
Answer: B
5) What is the definition of a compound in Dalton’s Atomic Theory?
A) All compounds are alike in mass and other properties.
B) Compounds are formed when atoms of different elements unite in the same proportions.
C) The relative numbers of each kind of atom in a compound form a simple ratio.
D) All compounds contain the same numbers of protons and neutrons.
6) Which is correct regarding an endothermic reaction?
A) The sign of the H is positive.
B) The reaction liberates heat.
C) The temperature increases when the reaction is carried out in a calorimeter.
D) The reaction does not occur.
E) The enthalpy of the reactants is higher than the enthalpy of the products.
Answer: A
7) When 10 g samples of the following materials absorb 100 J of heat, the temperature increase indicated is observed. Which material has the largest specific heat?
A) water, 2 K B) wood, 6 K C) cement, 11 K D) glass, 12 K E) copper, 26 K Answer: A
8) A 1.45 g sample of an iron ore is dissolved in acid and the iron obtained is Fe2
+
(aq). To titrate the solution, 21.6 mL of 0.102 M KMnO4-
(aq) is required. What is the percent of iron in the ore?5 Fe2
+
+ MnO4-
+ 8 H+
5 Fe3+
+ Mn2+
+ 4 H2OA) 57.6 B) 84.8 C) 61.5 D) 42.4 E) 8.6
Answer: D
9) After balancing the following redox equation, the sum of the stoichiometric coefficients on the right hand side of the equation is:
Cu2
+ +
Ce3+
CeO2+
Cu°
A) 3. B) 7. C) 11. D) 9. E) 2.
Answer: C
10) The mass of sodium chloride relative to the mass of a carbon-12 atom is expressed as the term:
A) molecular mass B) formula mass C) empirical mass D) structural mass
E) atomic mass Answer: B
11) The density of an unknown element in the gaseous state is 1.60 g L-1 at 300 K and 1 atm. Which of the following could be the element?
A) O2 B) He C) Cl2 D) Ne E) Ar
Answer: E
12) In light of the following thermochemical equation,
2 H2 (g)
+
O2 (g) 2 H2O (l) H° = -571.6 kJwhat volume of H2 (g), measured at 27°C and 745 torr, must be burned in excess oxygen to release 1000. kJ of heat to the surroundings?
A) 22.0 L B) 109 L C) 44.0 L D) 5.21 × 10-3 L E) 87.9 L
Answer: E
13) Which reaction classification is incorrectly labeled?
A) Ni2+ (aq)
+
S2- ( aq) NiS (s), neutralization B) H+ (aq)+
OH- (aq) H2O (l), neutralizationC) CH3COOH (aq)
+
OH- (aq) H2O (l)+
CH3COONa (aq), acid-baseD) 3 CH3CH2OH (l)
+
Cr2O72- (aq)+
8 H+
(aq) 3 CH3CHO (aq)+
2 Cr3+
(aq)+
7 H2O (l), oxidation-reductionE) 12 H2O (l)
+
2 P4 (s) 5 PH3 (g)+
3 H3PO4 (aq), disproportionation Answer: A14) Given the thermochemical equation:
2 NO (g)
+
O2 (g) 2 NO2 (g) H° = -114.0 kJcalculate H° for the following reaction:
NO2 (g) NO(g)
+
12 O2 (g)A) +128 kJ B) +57.0 kJ C) -57.0 kJ D) +114.0 kJ E) -114 kJ
Answer: B
15) Calculate the molarity of Br- ions in 250. mL of a solution containing 25.9 g NaBr and 0.155 moles of HBr.
A) 1.00 B) 1.626 C) 1.55 D) 0.155
E) Additional information is necessary.
Answer: B
16) Equal moles of H2, N2, O2, and He are placed into separate containers at the same temperature. Assuming each gas behaves ideally, which container has the highest pressure?
A) N2 B) He C) H2 D) O2
E) They would all exhibit the same pressure.
17) Given the following equation,
2 H2 (g) + O2 (g) 2 H2O (l) H° = -571.6 kJ, which statement is incorrect?
A) The equation forming gaseous water would have a different H°.
B) H° for the reverse reaction is +571.6 kJ.
C) The standard heat of formation of liquid water is -571.6 kJ/mol.
D) H° for forming one mole of liquid water is -285.8 kJ.
E) H° for the reaction of one-half mole of oxygen is -285.8 kJ.
Answer: C
18) When an exothermic reaction is carried out in a coffee-cup calorimeter, what statement is correct?
A) The
q
H2O is negative.B) The temperature of the water decreases.
C) The reaction absorbs heat from the water.
D) The enthalpy of the products is lower than that of the reactants.
E) The enthalpy change for the reaction is positive.
Answer: D
19) Which of the following reactions is not a redox reaction? Some of the reactions may not be balanced.
A) Ni2
+ +
Fe3+
Fe2+ +
Ni B) 2 Al+
Fe2O3 2 Fe+
Al2O3C) Bi3
+ +
Fe3+
BiO3- +
Fe2+
D) H
+ +
OH-
H2O E) NH3
+
NO N2+
H2OAnswer: D
20) A sample of hydrogen gas is contained in a balloon. The volume of the balloon is 2.15 L at 15°C. The
temperature is changed until the volume of the balloon is 3.25 L. What is the new temperature of the gas in °C?
A) 191 B) 162 C) 435 D) 23 E) -82
Answer: B
21) Which statement is incorrect regarding reduction?
A) Reduction is a "gain" of electrons.
B) Reduction is an increase in oxidation state.
C) Reduction is always accompanied by oxidation.
D) Reduction is the loss of O atoms.
E) none of these Answer: B
22) Consider 0.1 M solutions of the following substances. Which would have the greatest electrical conductivity?
A) HCl B) Ca(OH)2 C) CH3COOH D) CH3NH2 E) NH4Br
Answer: B
23) A sample of neon gas has a volume of 2.50 L at 780. torr and 24°C. How many neon atoms are in the sample?
A) 5.72 × 1024 B) 4.81 × 1025 C) 6.32 × 1022 D) 6.02 × 1023
E) none of the above Answer: C
24) Given a 100 g sample of each of the following liquids at 25°C, which would have the highest temperature after a 1.00 g of iron (sp heat = 0.449 J g-1 °C-1) at 50°C was added?
A) methanol (sp heat = 2.51 J g-1 °C-1) B) mercury (sp heat = 0.139 J g-1 °C-1) C) ethanol (sp heat = 2.46 J g-1 °C-1) D) ethylene glycol (sp heat = 2.35 J g-1 °C-1)
E) water (sp heat = 4.184 J g-1 °C-1) Answer: B
25) The standard enthalpy change for the following reaction is -72.8 kJ.
H2 (g)
+
Br2 (l) 2 HBr (g) What is the standard enthalpy of formation of hydrogen bromide?A) -145.6 kJ B) -72.8 kJ C) 72.8 kJ D) -36.4 kJ
E) none of the above Answer: D
26) In the reaction Cu (s) + 2 Ag
+
(aq) Cu2+
(aq) + 2 Ag (s). the reducing agent (if any) is A) Ag+
.B) Ag.
C) Cu2
+
.D) Cu.
E) none of these (not a redox reaction) Answer: D
27) HCl and NH3 react to form a white solid, NH4Cl. If cotton plugs saturated with aqueous solutions of each are placed at the ends of a glass tube 60.0 cm long, calculate the distance from the HCl end that the white ring will form.
A) 35.7 cm B) 24.3 cm C) 29.6 cm D) 40.9 cm E) 19.1 cm
Answer: B
28) Use the following thermochemical equations
C2H5OH (l)
+
3 O2 (g) 2 CO2 (g)+
3 H2O (l) H° = -1367 kJ H2 (g)+
1/2 O2 (g) H2O (l) H° = -286 kJC (gr)
+
O2 (g) CO2 (g) H° = -394 kJ to calculate the enthalpy change for the reaction2 C (gr)
+
3 H2 (g)+
1/2 O2 (g) C2H5OH (l) H° = ?A)
-
279 kJ B)+
2047 kJ C)+
687 kJ D)+
279 kJ E)+
680 kJAnswer: A
29) How many grams of iron are formed by the reaction of 6.0 g Al with excess iron oxide, according to the following unbalanced equation?
Al
+
Fe2O3 Fe+
Al2O3A) 12 B) 0.22 C) 6.0 D) 24 E) 18
Answer: A
30) A 125-mL tank is charged with oxygen until the pressure is 75.0 atm at 25°C. Calculate the moles of oxygen in the tank.
A) 0.383 B) 0.00378 C) 4.57 D) 383 E) 0.505
Answer: A
31) Which statement is not correct?
A) Internal energy, E, is a state function.
B) Heat and work are state functions.
C) The enthalpy change is the heat of reaction at constant pressure.
D) Enthalpy is a state function.
E) Heat is given off to the surroundings in an exothermic reaction.
Answer: B
32) Vinegar is an aqueous solution of acetic acid, CH3COOH. A 5.00 mL sample of a particular vinegar requires 26.90 mL of 0.175 M NaOH for its titration. What is the molarity of acetic acid in the vinegar?
A) 1.04 B) 0.175 C) 0.471 D) 0.520 E) 0.942
Answer: E
33) Which of the following is an example of an object possessing potential energy?
A) a bird perched in a tree B) a rock on a beach C) a penny on the floor D) a snake in the grass
E) a boulder in a valley Answer: A
34) When the following reaction is balanced in base with lowest ratio coefficients, what is the coefficient of H2O and on which side is the water?
Al (s)
+
ClO- (aq) Al(OH) 4-
(aq)+
Cl-
(aq) A) 3 on left
B) 2 on left
C) 0, H2O doesn't appear in the balanced equation.
D) 1 on right E) 2 on right Answer: A
35) Equal volumes of an unknown gas and nitrogen (N2) gas take 5.37 min and 3.55 minutes, respectively, to effuse through a small hole. Calculate the molar mass (in g/mol) of the unknown gas.
A) 128 B) 42.4 C) 64.1 D) 18.5 E) 12.2
Answer: C
36) What is the change in internal energy of a system that absorbs 635 J of heat and does 249 J of work?
A) 635 J B) 386 J C) -386 J D) 884 J E) -635 J
Answer: B
37) Considering the following reaction, what statement is incorrect?
Cu (s)
+
4 H+
(aq)
+
2 NO3-
(aq) Cu2+
(aq)+
2 NO2 (g)+
2 H2O (l)A) NO3
-
is the oxidizing agent.B) NO3
-
is reduced.C) Cu2
+
is the result of an oxidation.D) Cu is oxidized.
E) Cu is the oxidizing agent.
Answer: E
38) Which of the following is not a strong electrolyte?
A) NaCl B) KBr C) HOCl2 D) CH2Cl2 E) HCl
Answer: D
39) When nitroglycerin explodes, it decomposes to a mixture of different gases. Hence, nitroglycerin is : A) an ion
B) a compound and is also a molecule C) a molecule
D) a compound E) an element Answer: B
40) At 25°C and constant pressure, carbon monoxide gas combines with oxygen gas to give carbon dioxide gas with the evolution of 10.1 kJ per gram of carbon monoxide consumed. What is the value of H for the balanced reaction?
A) 283 kJ/mol B) -141 kJ/mol C) -283 kJ/mol D) -566 kJ/mol E) 141 kJ/mol Answer: D
41) A sample of hydrogen gas was collected over water at 21°C and at a pressure equal to the atmospheric pressure of 748 mm Hg. The volume of the sample was 512 mL. How many grams of H2 are in the sample? The vapor pressure of water at 21°C is 18.7 mm Hg.
A) 0.0422 g B) 15.5 g C) 0.0411 g D) 0.0203 g E) 15.9 g
Answer: C
42) When heat is absorbed by the system from the surroundings, the process is said to be __________, and the sign of process is __________.
A) exothermic; negative B) endothermic; positive C) endothermic; negative D) spontaneous; positive
E) exothermic; positive Answer: B
43) How many liters of a 3.85 M solution of Fe2
+
are needed to titrate 250.0 mL of a 0.125 M CrO 2-4 solution?H
+ +
CrO42-+
Fe2+
Fe3+ +
Cr2O3+
H2O (not balanced)A) 0.0487 B) 4.87 C) 4.06 D) 0.0244 E) 8.12
Answer: D
44) Which of the following is an example of an object possessing kinetic energy?
A) a stick of dynamite B) a boulder resting on a cliff C) water at the top of a dam D) a ball rolling downhill
E) a bird perched in a tree Answer: D
45) Which of the following aqueous solutions has the highest total concentration of H+ ions?
A) 1.2 M NaOH B) 55.6 M H2O C) 0.25 M HCl D) 1.0 M CH4 E) 0.20 M NaH
Answer: C
46) When the following half reaction (unbalanced) occurs, the number of electrons transferred per mole of Br2 is:
Br2 (aq) BrO3
-
(aq)A) 1. B) 8. C) 5. D) 10. E) 2.
Answer: D
47) What mass of CH4 (g) must be burned to release 334 kJ of heat to the surroundings?
CH4 (g)
+
2 O2 (g) CO2 (g)+
2 H2O (l) H° = -890 kJA) 0.375 g B) 0.426 g C) 55.6 g D) 6.00 g E) 2.66 g
Answer: D
48) A gas sample containing N2 and O2 was found to contain 72% N2. If the pressure of the sample was 2.0 atm, what is the partial pressure of O2?
A) 1.44 atm B) 0.43 atm C) 0.28 atm D) 0.56 atm E) 0.72 atm
Answer: D
49) Which of the following is NOT a component of internal energy?
A) reactivity B) vibrations C) rotations
D) intermolecular forces E) translations
Answer: A
50) Given the following data, what is the enthalpy of the reaction at 25°C shown below?
( Hf ° (H+) = 0.0 kJ/mol; Hf ° (OH-) = -230.0 kJ/mol; Hf ° (H2O) = -285.8 kJ/mol) H
+
(aq) + OH- (aq) H2O (l)A) 55.8 kJ/mol B) -515.8 kJ/mol C) 515.8 kJ/mol D) -55.8 kJ/mol E) 230.0 kJ/mol Answer: D
