CHEM Final

20. A bomb calorimeter with a molar heat capacity of 4.31 kJ/°C combusted 1.21 g of acetone (molar mass 58.08 g/mol). The temperature rose by 8.8°C. What was the enthalpy of the reaction? (a) -2203 kJ/mol (b) -1820 kJ/mol (c) 2203 kJ/mol (d) 2665 kJ/mol

(b) -1820 kJ/mol

1. Which of the following statements about the First Law of Thermodynamics are true? I) The total energy of the universe is constant. II) Euniv = Esys + Esurr = 0 III) Esys = q - w A) I and II B) I and III C) II and III D) I, II and III

A) I and II

15. When 1.00 mol of benzene is vaporized at a constant pressure of 1.00 atm and at its normal boiling point of 80.1°C, 33.9 kJ are absorbed and PΔV for the vaporization process is equal to 2.90 kJ, then A) ΔE = 31.0 kJ and ΔH = 33.9 kJ. B) ΔE = 36.8 kJ and ΔH = 33.9 kJ. C) ΔE = 33.9 kJ and ΔH = 31.0 kJ. D) ΔE = 33.9 kJ and ΔH = 36.8 kJ.

A) ΔE = 31.0 kJ and ΔH = 33.9 kJ.

4. Which one of the following aqueous solutions should have the lowest freezing point: 0.0500 m C6H12O6 (glucose), 0.0300 m KBr, or 0.0150 m Na2SO4? A: 0.0300 m KBr B: 0.0500 m C6H12O6 C: 0.0150 m Na2SO4 D: They all have the same freezing point

A: 0.0300 m KBr

12. For a process at constant volume, A) q = 0, w = 0, and ΔE = 0. B) w = 0 and ΔE = q. C) w = 0 and ΔH = q. D) w = 0 and ΔE = ΔH.

B) w = 0 and ΔE = q.

19. Vinegar contains acetic acid (CH3COOH, 60.06 g/mol). The acetic acid in a 12.0 g sample of vinegar was neutralized by 84.0 mL of 0.250 M NaOH. What is the mass percent CH3COOH in this type of vinegar? A. 6.01% B. 10.5% C. 21.8% D. 32.4%

B. 10.5%

14. The volume of a weather balloon is 200.0 L and its internal pressure is 1.17 atm when it is launched at 20°C. The balloon rises to an altitude in the stratosphere where its internal pressure is 63 mmHg and the temperature is 210 K. What is the volume of the balloon then? A: 1.42x103 L B: 2.02x103 L C: 6.12x103 L D: 7.06x103 L

B: 2.02x103 L

17. At 20°C, the vapor pressure of ethanol (CH3CH2OH) is 45 torr and the vapor pressure of methanol (CH3OH) is 92 torr. What is the vapor pressure at 20°C of a solution prepared by mixing 25 g of methanol and 75 g of ethanol? A: 24 torr B: 60 torr C: 74 torr D: 122 torr

B: 60 torr

18. Cinnamon owes its flavor and odor to cinnamaldehyde (C9H8O). Determine the freezing point of a solution of 75 mg of cinnamaldehyde dissolved in 1.00 g of benzene (Kf = 4.3°C/m; normal freezing point = 5.5°C). A: 2.4 oC B: 1.6 oC C: 3.1 oC D: 7.9 oC

C: 3.1 oC

22. A bottle is half-filled with a 1:3 (by moles) mixture of heptane (C7H16) and octane (C8H18) at 25°C. What is the mole fraction of heptane in the vapor in the air space above the liquid in the bottle? The vapor pressures of heptane and octane at 25°C are 31 torr and 11 torr, respectively. A: 0.25 B: 0.55 C: 0.67 D: 0.48

D: 0.48

15. Isooctane is used to grade gasoline. Its boiling point is 99 oC, and the heat of evaporation is 35.2 kJ/mol. What is the vapor pressure of isooctane at 25 oC in torr? A: 12 torr B: 22 torr C: 38 torr D: 45 torr

D: 45 torr

21. The freezing point of a solution prepared by dissolving 1.50 × 102 mg of caffeine in 10.0 g of camphor is 3.07°C lower than that of pure camphor (Kf = 39.7°C/m). Elemental analysis of caffeine yields the following results: 49.49% C, 5.15% H, 28.87% N, and the remainder (16.49%) is O. What is the molecular formula of caffeine? A: C4H5N2O B: C4H12N4O2 C: C8H16N6O2 D: C8H10N4O2

D: C8H10N4O2

18. Toxic chromate can be precipitated from an aqueous solution by bubbling SO2 through the solution. How many grams of SO2 are required to treat 3.0 × 108 L of 0.050 mM Cr6+? 2 CrO4 2-(aq) + 3 SO2(g) + 4 H+(aq) → Cr2(SO4)3(s) + 2 H2O(ℓ) a) 1.4x106 g b) 2.3x107 g c) 3.6x108 g d) 5.4x105 g

a) 1.4x106 g

7. Rank the following ions in the order of decreasing oxidation number of chlorine a) ClO4 - > ClO3 - > ClO2 - > ClO- b) ClO2 - > ClO- > ClO4 - > ClO3 - c) ClO3 - > ClO2 - > ClO- > ClO4 - d) ClO- >ClO2 - > ClO3 - > ClO4 -

a) ClO4 - > ClO3 - > ClO2 - > ClO-

5. A gas occupies a container. Using your knowledge of the ideal gas law, if you were to double the volume of the container while keeping temperature and moles constant, what will happen to the pressure? a) Decrease by half. b) Increase by a factor of 2. c) Remain constant. d) It will increase exponentially.

a) Decrease by half.

14. Exactly 10.0 mL of water at 25.0°C is added to a hot iron skillet. All of the water is converted into steam at 100.0°C. The mass of the pan is 1.20 kg. What is the change in temperature of the skillet? a) T= -47.5 oC b) T= -35.4 oC c) T= -23.3 oC d) T= -17.6 oC

a) T= -47.5 oC

6. Oxalic acid (H2C2O4), a diprotic acid that is used in bleaching applications, can be toxic in high amounts when ingested. In 200 grams of parsley, there are about 0.04 moles of oxalic acid. Which of the following would completely neutralize this quantity of oxalic acid? a. 0.1 L of 0.8 M NaOH b. 0.4 L of 0.3 M KOH c. 0.25 L of 0.08 M KOH d. 0.15 L of 0.004M Ca(OH)2

a. 0.1 L of 0.8 M NaOH

11. A gaseous mixture contains 1.97 mol Argon, 1.3 mol Oxygen, and 0.81 mol Neon. If the total pressure of the mixture is 1.32 atm, what is the partial pressure of Argon? a. 0.638 atm b. 1.121 atm c. 0.722 atm d. 0.363 atm

a. 0.638 atm

19. What is the vapor pressure of an aqueous solution that has a solute mole fraction of c = 0.100? The vapor pressure of water is 25.756 mmHg at 25°C. a. 23.2 mmHg b. 2.58 mmHg c. 25.8 mmHg d. 22.3 mmHg

a. 23.2 mmHg

9. An unknown gas effuses 1.89 times faster than N2O4 at the same temperature. What is the molar mass of the unknown gas? a. 25.78 g/mol b. 16.45 g/mol c. 63.22 g/mol d. 124.26 g/mol

a. 25.78 g/mol

13. The Henry's law constant for oxygen dissolving in blood is 3.74x10-2 mol/L · atm at body temperature, 37°C. Calculate the molar concentration of oxygen in blood for an alpine climber where the atmospheric pressure is 0.45 atm. The mole fraction of oxygen in air is 0.209. a. 3.5x10-3 M b. 2.7x10-3 M c. 1.6x10-2 M d. 1.2x10-2 M

a. 3.5x10-3 M

6. The initial internal energy of a system is 43.5 kJ. It absorbs 8.3 kJ of heat while performing 3.5 kJ of work on the surroundings. What is its final internal energy? a. 48.3 kJ b. 55.3 kJ. c. 38.7 kJ d. 31.7 kJ

a. 48.3 kJ

2. In the following equation does water act as an acid or a base? NH3(aq) + H2O( ) NH4 +(aq) + OH- (aq) a. Acid b. Base c. Both d. Neither

a. Acid

9. In which of the following does manganese have the highest oxidation number? a. Ba(MnO4)2 b. Mn(NO3)2 c. MnO2 d. K2MnO4

a. Ba(MnO4)2

5. In the smelting of iron from iron oxide according to the equation, which is oxidized? Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g), a. C in CO b. C in CO2 c. Fe in Fe2O3 d. O in Fe2O3

a. C in CO

3. The density of a pure gas at STP depends on its __________ a. Molar mass b. Concentration c. Temperature d. Volume

a. Molar mass

1. The pressure of a gas is inversely proportional to a. the volume of the gas. b. the number of gas particles. c. the temperature of the gas. d. the mass of gas.

a. the volume of the gas.

1. How many moles of all ions are present in exactly 150 mL of a 0.260 M ammonium phosphate solution, (NH4)3PO4(aq)? a) 1.04 mol b) 0.156 mol c) 0.0390 mol d) 0.312 mol

b) 0.156 mol

15. If the absorbance of a solution of copper(II) ion decreases by 41.00% upon dilution, what volume of water was added to 20.0 mL of a 1.20 M solution of Cu2+(aq)? a) 11.10 mL b) 13.90 mL c) 25.40 mL d) 36.20 mL

b) 13.90 mL

17. To balance the following redox equation under the conditions indicated, what is the coefficient of Mn2+? Mn2+(aq) + O2(g) → MnO2(s) (basic solution) a) 1 b) 2 c) 4 d) 8

b) 2

6. At what temperature will 3.00 mole of an ideal gas in a 9.00 L exert a pressure of 10.00 atm? (R = 0.08206 L*atm*K−1*mol−1) a) 77.92 K b) 365.6 K c) 40.62 K d) 298.2K

b) 365.6 K

10. The heating curve for a substance is shown below. The substance initially is a solid. It then becomes a liquid and a gas. Which of the line segments (I-V) represents the solid-toliquid phase transition a) I b) II c) III d) IV

b) II

18. Determine the change in enthalpy for the following reaction from the enthalpies of formation for the reactants and products. (C2H2Cl2 , + 4.27 kJ/mol; C2H2Cl4 , −155.6 kJ/mol) a). +151.3 kJ/mol b). −159.9 kJ/mol c). +153.1 kJ/mol d). −151.3 kJ/mol

b). −159.9 kJ/mol

16. Use the bond energies in the table below to estimate the enthalpy change associated with the hydrogenation reaction of acetylene. HC CH(g) + 2 H2(g) CH3CH3(g) Bond C C C—C CH HH Energy (kJ/mol) 839 348 413 436 a. 489 kJ/mol b. -289 kJ/mol c. -725 kJ/mol d. -5363 kJ/mol

b. -289 kJ/mol

1. A 1.50 mol sample of He occupies a volume of 2.50 L at a pressure of 14.7 atm. What will be the pressure of a 1.50 mol sample of H2 gas under the same conditions? a. 7.33 atm b. 14.7 atm c. 29.4 atm d. Can not be calculated as T is not known

b. 14.7 atm

2. A sample of oxygen gas at 25.0°C has its pressure tripled while its volume is halved. What is the final temperature of the gas? a. -74.3°C b. 174°C c. 447°C d. 49.7°C

b. 174°C

3. Which of the following should have the highest conductivity? a. 3.0 M NaCl b. 2.1 M Na3PO4 c. 2.4 M CaCl2 d. 3.2 M NH4NO3

b. 2.1 M Na3PO4

10. A sample of nitrogen gas at 25.0°C has its pressure quadrupled while its volume is halved. What is the final temperature of the gas? a. 174 oC b. 323 oC c. 596 oC d. 447 oC

b. 323 oC

16. Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have normal boiling points less than 100°C. Is this observation consistent with the following equation? Tb = iKbm a. No, boiling point elevation pertains only to ionic solutes. b. No, boiling point elevation pertains only to nonvolatile solutes. c. Yes, boiling point depression occurs for all solutions. d. Yes, the boiling point depression constant for isopropyl alcohol is large

b. No, boiling point elevation pertains only to nonvolatile solutes.

5. Which of the following will always increase the internal energy of a system? a. The system gains energy and performs work b. The system gains energy and work is performed on it. c. The system loses energy and performs work d. The system loses energy and work is performed on it

b. The system gains energy and work is performed on it.

8. Tube worms obtain energy by the oxidation reaction of H2S to SO4 2-. What is the overall change in the oxidation number of sulfur for this reaction? a) +4 b) +6 c) +8 d) +12

c) +8

22. Calculate the enthalpy of reaction for the conversion of iron(II) oxide in carbon monoxide to iron metal and carbon dioxide using the following reaction information. Fe2 O3(s) + 3 CO(g) = 2 Fe(s) + 3CO2(g) H°rxn = -23 kJ 3 Fe2O3(s) + CO(g) = 2 Fe3O4(s) + CO2(g) H°rxn = -39 kJ Fe3O4(s) + CO(g) = 3 FeO(s) + CO2(g) H°rxn = +18 kJ FeO(s) + CO(g) = Fe(s) + CO2(g) H°rxn = ? a) -45 kJ b) -24 kJ c) -11 kJ d) -66 kJ

c) -11 kJ

20. In an experiment, 26.5 g of metal was heated to 98.0°C and then quickly transferred to 150.0 g of water in a calorimeter. The initial temperature of the water was 26.5°C, and the final temperature after the addition of the metal was 32.5°C. Assume the calorimeter behaves ideally and does not absorb or release heat. Specific heat capacity of water is 4.18 J/g oC. What is the value of the specific heat capacity (in J/g•°C) of the metal? a) 1.6 J/g oC b) 4.3 J/g oC c) 2.2 J/g oC d) 6.1 J/g oC

c) 2.2 J/g oC

21. In an experiment, 10.0 g of ice at -20.0°C is converted into steam with a temperature of 110.0°C. How much energy is required for this process? Hvap = 2260 J/g; Hfus = 334 J/g; cp (ice) = 2.06 J/(g °C); cp(water) = 4.18 J/(g °C); cp(steam) = 1.99 J/(g °C) a) 26.5 kJ b) 28.4 kJ c) 30.7 kJ d) 32.4 kJ

c) 30.7 kJ

13. For the reaction, H2SO4(aq) + NaCl(aq) + MnO2(s) MnCl2(aq) + H2O(ℓ)+ Cl2(g) + Na2SO4(aq) After balance the redox reaction, what is the coefficient of NaCl? a) 1 b) 2 c) 4 d) 6

c) 4

21. Combustion of one mole of anethole (C10H12O) produces 5541 KJ of thermal energy. If 0.950 g of anethole is combusted in a bomb calorimeter whose heat capacity (Ccalorimeter ) is 7.854 kJ/oC, what is the change of the temperature of the calorimeter? The molar mass of anethole is 148.20 g/mol. a) 1.44 oC b) 3.68 oC c) 4.52 oC d) 6.16 oC

c) 4.52 oC

4. What is the oxidation number of Mn in K2MnO4? a) 2 b) 4 c) 6 d) 7

c) 6

11. A system performs work on the surroundings but no thermal energy is transferred. Which of the following is true from the system's perspective? (q = heat, w = work, ΔE = internal energy change) a) q = 0, w > 0, ΔE > 0 b) q = 0, w > 0, ΔE < 0 c) q = 0, w < 0, ΔE < 0 d) q < 0, w > 0, ΔE = 0

c) q = 0, w < 0, ΔE < 0

17. Given the following reactions, what is the overall enthalpy change in converting 1.00 mol of silicon dioxide into pure silicon? a) +592 kJ b) −1972 kJ c) −592 kJ d) −625 kJ

c) −592 kJ

6. What would be the freezing point of a 1.00 m solution of KCl in water? (K f = 1.86°C) a. 0.0°C b. -1.86 °C c. -3.72 °C d. -4.16°C

c. -3.72 °C

12. A solution contains 100.0 g of water (MW = 18.0 g/mol) and 25.00 g of ethanol (MW = 44.0 g/mol). What is the mole fraction of water in vapor at 25°C? (Powater = 23.8 torr; Poethanol = 58.7 torr) a. 0.20 b. 0.09 c. 0.80 d. 0.91

c. 0.80

19. In a specific region, lead levels in drinking water are said to be no higher than 25 ppb. What is this in mol/L? The atomic mass of Pb is 207.2 g/mol. Assume the density of drinking water is 1.0 g/mL and assume you have 1g of water for calculation. a. 7.2 x10-8 M b. 6.2 x10-5 M c. 1.2x10-7 M d. 3.2x10-8 M

c. 1.2x10-7 M

5. Calculate the minimum pressure that must be applied to achieve reverse osmosis of 0.504 M NaCl at 22°C a. 0.906 atm b. 12.2 atm c. 24.4 atm d. 92.2 atm

c. 24.4 atm

3. How many grams of KMnO4 (molar mass = 158.034 g/mol) is needed to make 400.0 mL of a 0.400 M solution a. 12.5 g b. 16.0 g c. 25.3g d. 8.0g

c. 25.3g

8. Which of the following pairs of liquids probably exhibits very nearly ideal behavior when mixed? a. CH3Br and CH3OCH3 b. CH3CN and H2O c. C7H16 and C8H18 d. CH3CH2OH and CH3COOH

c. C7H16 and C8H18

10. Approximately 192 grams of ammonium nitrate (80.0 g/mol) will dissolve in 100 grams of water at 20°C (solubility). If 21.0 mol NH4NO3 is dissolved in 875 g H2O, the solution is a. unsaturated. b. supersaturated. c. saturated. d. dilute

c. saturated.

12. Fuel value is a. the cost of energy in kJ/$. b. the amount of energy contained in 1 mol of a substance (kJ/mol). c. the energy released when 1 g of a substance is burned (kJ/g). d. the energy released when 1 g of a substance is formed (kJ/g).

c. the energy released when 1 g of a substance is burned (kJ/g).

14. Calculate the molarity of an acetic acid solution if 34.57 mL of this solution are needed to neutralize 25.19 mL of 0.1025 M sodium hydroxide CH3COOH (aq) + NaOH (aq) Na+(aq) + CH3COO-(aq) + H2O (l) a) 0.1262 M b) 0.2276 M c) 0.02362 M d) 0.07469 M

d) 0.07469 M

11. Given 200.0 g of hot tea at 80.0 oC, what mass of ice at 0 oC must be added to obtain iced tea at 10.0 oC? The specific heat of the tea is 4.18 J/(g •oC), and Hfusion for ice is +6.01 kJ/mol. a) 311.2 g b) 77.8 g c) 175.2 g d) 155.6 g

d) 155.6 g

16. Given 200.0 g of hot tea at 80.0 oC, what mass of ice at 0 oC must be added to obtain iced tea at 10.0 oC? The specific heat of the tea is 4.18 J/(g •oC), and Hfusion for ice is +6.01 kJ/mol. a) 311.2 g b) 77.8 g c) 175.2 g d) 155.6 g

d) 155.6 g

22. Calculate the mass of MgCO3 precipitated by mixing 10.0 mL 0f a 0.200 M Na2CO3 solution with 5.00mL of 0.0500M Mg(NO3)2 solution. The molar mass of MgCO3 (84.31 g/mol). a) 4.24x10-4 g b) 1.22x10-3 g c) 3.42x10-2 g d) 2.11x10-2 g

d) 2.11x10-2 g

9. Which species is oxidized in the reaction 2 N2H4(g) + N2O4(s) = 3 N2(g) + 4 H2O(g)? a) H in N2H4 b) O in N2O4 c) N in N2O4 d) N in N2H4

d) N in N2H4

2. In aqueous solution, the dihydrogen phosphate ion a) acts as an acid. b) acts as a base. c) acts neither as an acid nor as a base. d) can serve as both an acid and as a base.

d) can serve as both an acid and as a base.

20. Acid precipitation dripping on limestone produces carbon dioxide by the following reaction: CaCO3(s) + 2 H+(aq) → Ca2+(aq) + CO2(g) + H2O(ℓ) If 8.6 mL of CO2 were produced at 15°C and 760 mmHg, then how many milligrams of CaCO3 were consumed? a. 0.127 g b. 0.228 g c. 0.431 g d. 0.0364 g

d. 0.0364 g

7. The concentration of copper(II) sulfate (MW=159.6 g/mol) in one brand of soluble plant fertilizer is 0.017% by mass. If a 30 g sample of the fertilizer is dissolved in 2.0 L of solution, what is the molarity of Cu2+? a. 4.4x10-5 M b. 3.3x10-6 M c. 8.0x10-6 M d. 1.6x10-5 M

d. 1.6x10-5 M

8. In a specific region, lead levels in drinking water are said to be no higher than 35 ppb. What is this in mol/L? The atomic mass of Pb is 207.2 g/mol. Assume the density of drinking water is 1.0 g/mL and assume you have 1g of water for calculation. a. 7.2 x10-8 M b. 6.4 x10-5 M c. 3.2x10-7 M d. 1.7x10-7 M

d. 1.7x10-7 M

7. The Henry's law constant for oxygen dissolving in blood is 3.74 10-2 mol/L atm at body temperature, 37°C. Calculate the molar concentration of oxygen in blood for a scuba diver where the air pressure is 3.0 atm. The mole fraction of oxygen in air is 0.209. a. 7.8 x 10-3 M b. 2.7 x 10-3 M c. 1.6 x 10-2 M d. 2.3 x 10-2 M

d. 2.3 x 10-2 M

13. A 20.0 g piece of iron and a 20.0 g piece of gold at 100.0°C are dropped into 1.00 L of water at 20.0°C. What is the final temperature of the water and pieces of metal? Given cp (Fe) = 0.45 J/g oC, cp (Au) = 0.129 J/g oC. cp (H2O) = 4.18 J/g oC a. 24.2 oC b. 22.6 oC c. 28.2 oC d. 20.2 oC

d. 20.2 oC

2. Which of the following statements regarding the mixing of gases is correct? a. More massive gases settle to the bottom of a container, leaving lighter gases near the top. b. The relative proportions of gases in a mixture vary throughout the container, depending on the pressure. c. Nonpolar gases do not mix with polar gases. d. All gas mixtures are homogeneous.

d. All gas mixtures are homogeneous.

4. What is the formula of the precipitate that forms when aqueous ammonium phosphate and aqueous copper(II) chloride are mixed? a. Cu3P2 b. Cu(NH4)2 c. Cu2PO3 d. Cu3(PO4)2

d. Cu3(PO4)2

4. Which one of the following statements is NOT correct? a. A decrease in temperature causes a decrease in gas pressure because the frequency of molecules colliding with the wall decreases b. An increase in pressure is observed as temperature of a gas increases because the average force of molecules colliding with the wall increases c. Gases often deviate from ideal behavior at sufficiently high pressures and low temperatures d. The PV/nRT ratio for real gases can be greater than 1 because of the attractive forces between molecules.

d. The PV/nRT ratio for real gases can be greater than 1 because of the attractive forces between molecules.

3. Which of these gases (Ar, N2O, H2) has the same average kinetic energy at 25°C as CO2? a. Ar b. N2O c. H2 d. They are all the same as CO2

d. They are all the same as CO2