CH 101 FALL 2013 EXAM III

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Feb 20, 2024

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CH 101 EXAM III FALL 2013 NOVEMBER 22 nd , 2013 NAME:_______________________________________________ __________ / 125 points (6.25 points each, including the bonus)

1. What is the enthalpy change for the following reaction: C (s) + ½ O 2 (g) → CO (g) ΔH = ? Given that: C (s) + O 2 (g) → CO 2 (g) ΔH= -393.5 kJ CO (g) + ½ O 2 (g) → CO 2 (g) ΔH= -283.0 kJ (A) -676.5 kJ (B) -110.5 kJ (C) 0.00 kJ (D) 110.5 kJ (E) 676.5 kJ 2. Tungsten is the metal commonly used as the filament in incandescent light bulbs. If 1.233 kJ of heat is added to a 27.8 g tungsten wire at an initial temperature of 121 °C, what is the final temperature of the wire? The specific heat of tungsten is C s = 0.135 J/g °C. (A) 328 °C (B) 394 °C (C) 450 °C (D) 473 °C (E) 525 °C 3. Propane, C 3 H 8 , is a common gas used in outdoor cooking. It burns to form CO 2 and water. C 3 H 8 (g) + O 2 (g) → CO 2 (g) + H 2 O (g) ΔH= -2,044 kJ Calculate the ΔH associated with burning a sample of propane if 64.4 g of H 2 O are formed. (A) -18,230 kJ (B) -12,550 kJ (C) -9,653 kJ (D) -7,309 kJ (E) -2,390 kJ 4. Choose the set of quantum numbers below that is allowed to describe one of the highest energy orbital occupied by an electron in a Sulfur atom. (A) n=2, l=1, m l =0, m s =-1 (B) n=3, l=0, m l =1, m s =-1/2 (C) n=3, l=1, m l =-1, m s =+1/2 (D) n=3, l=1, m l =0, m s =2 (E) n=4, l=0, m l =0, m s =-1/2

5. Calculate the enthalpy change for the combustion of methane (natural gas): CH 4 (g) + 3/2 O 2 (g) → CO 2 (g) + H 2 O (g) ΔH= ? Given that, C (s) + H 2 (g) → CH 4 (g) ΔH= 74.6 kJ C (s) + O 2 (g) → CO 2 (g) ΔH= -393.5 kJ H 2 (g) + ½ O 2 (g) → H 2 O (g) ΔH= -483.6 kJ (A) -409 kJ (B) 14.9 kJ (C) -952 kJ (D) 803 kJ (E) -1,190 kJ 6. Assuming the samples of each of the metals listed below have the same mass and the same initial temperature, which will require the SMALLEST amount of heat to change its temperature 5.00 °C? ANSWER CHOICE Metal Specific Heat (J/g °C) (A) Au 0.128 (B) Mn 0.480 (C) Zr 0.0278 (D) Zn 0.388 (E) Fe 0.450 7. The addition of 3,310 J of heat to a 300.0 g sample of mercury at 19.0 ˚C caused the temperature of the sample to rise to 99.0 ˚C. What is the specific heat of mercury? (A) 41.4 J/g °C (B) 7.25 J/g °C (C) 0.581 J/g °C (D) 0.138 J/g °C (E) 0.111 J/g °C 8. An unknown substance is found to emit photons of light that have a frequency of 1.90 x 10 11 Hz, what is the energy of ONE MOLE of these photons? (A) 2.09 x 10 -46 J (B) 1.26 x 10 -22 J (C) 7.39 x 10 -5 J (D) 0.125 J (E) 75.8 J

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9. The following table lists the colors of visible light by their wavelength in nanometers. What is the color of photon whose energy is 3.98 x 10 -19 J? Color Wavelength Red 670 nm Orange 630 nm Yellow 600 nm Green 500 nm Blue 470 nm Purple 400 nm (A) Red (B) Orange (C) Green (D) Blue (E) none of these 10. The correct electron configuration for chlorine atom is: (A) 1s 2 2s 2 2p 6 3p 7 (B) [Ar]3s 2 3p 5 (C) 1s 2 2s 2 2p 6 3s 2 3p 5 (D) [Ne]3p 5 (E) [Ar]4s 2 3d 10 4p 5 11. The electron configuration for Co is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 7 4s 2 , how many electrons are unpaired for the Co orbital diagram? (A) 0 (B) 1 (C) 2 (D) 3 (E) 4 12. Which of the following orbitals could have the quantum numbers n=3, l=2, m l =2, m s =-½? (HINT – THE SMALL CIRCLE IS THE NUCLEUS OF THE ATOM) (A) (B) (C) (D) (E)

13. Sodium hydroxide and hydrogen react to produce sodium metal and water in an oxidation-reduction reaction. The balanced chemical equation below represents this reaction. If you allow 5.00 g of liquid water react with 15.0 g of solid sodium, how much energy is released? Na (s) + H 2 O (g) → NaOH (s) + ½ H 2 (g) ΔH = -425.93 kJ (A) 1.18 x 10 2 kJ (B) 2.78 x 10 2 kJ (C) -1.18 x 10 2 kJ (D) -2.78 x 10 2 kJ (E) 3.96 x 10 2 kJ 14. Octane is burned in automobiles via the following reaction: 2 C 8 H 18 (l) + 25 O 2 (g) → 16 CO 2 (g) + 18 H 2 O (l) ΔH o = -10,148 kJ If the automobile produces 2.00 kg of CO 2 (g) in 1 hour, how much energy is produced in that time? (A) 3.6 x 10 3 kJ (B) 2.88 x 10 4 kJ (C) 1.44 x 10 4 kJ (D) 7.23 x 10 3 kJ (E) 5.76 x 10 4 kJ 15. Given that: 2 H 2 (g) + O 2 (g) → 2 H 2 O (l) ΔH o = - 571 kJ/mol C 3 H 4 (g) + 4 O 2 (g) → 3 CO 2 (g) + 2 H 2 O (l) ΔH o = - 1941 kJ/mol C 3 H 8 (g) + 5 O 2 (g) → 3 CO 2 (g) + 4 H 2 O (l) ΔH o = - 2220 kJ/mol Calculate ΔH o for the reaction: C 3 H 4 (g) + 2 H 2 (g) → C 3 H 8 (g) (A) -292 kJ/mol (B) 292 kJ/mol (C) 850 kJ/mol (D) -850 kJ/mol (E) -3590 kJ/mol

16. A coffee cup calorimeter is used to measure the heat of solvation for the following reaction: NaOH (s) → OH - (aq) + Na + (aq) ΔH solv = ? What is the heat of solvation (ΔH solv ) in J/mol NaOH if the measured temperature change is 5.215 °C, for a 20.0 g sample of NaOH that is dissolved in 1.00 L of water? (assume the specific heat of the solution is the same as water, C s = 4.18 J/g °C) (A) ΔH solv = 44.5 J/mol (B) ΔH solv = -44.5 J/mol (C) ΔH solv = -22.3 J/mol (D) ΔH solv = -50.6 J/mol (E) ΔH solv = 22.3 J/mol 17. Aroldis Chapman currently holds the record for the fastest pitch in an official Major League Baseball game. The pitch was recorded at 105.9 m/h (miles per hour). What is the De Broglie wavelength of the fastball? The average mass of a baseball is 0.145 kg and 1.00 m/h = 0.447 m/s. (A) 2.31 x 10 34 m (B) 4.31 x 10 -35 m (C) 9.65 x 10 -35 m (D) 2.76 x 10 -34 m (E) 1.03 x 10 34 m 18. Red (λ = 670 nm) is one of the colors of light emitted when an excited electron in a hydrogen atom transitions to a lower energy state. What is the energy difference between the two allowed quantum levels? (A) 2.96 x 10 -19 J (B) 3.15 x 10 -19 J (C) 3.31 x 10 -19 J (D) 3.97 x 10 -19 J (E) 4.23 x 10 -19 J 19. Choose the electron configuration for the P 3- anion. (A) [Ne]3s 2 3p 3 (B) [Ne]3s 2 (C) [Ar]4s 2 4p 1 (D) [Ar] (E) [Ne]

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20. What atom is represented by the electron configuration in the orbital diagram below? 4d ↑ ↑ ↑ ↑ ↑ 5s ↑ ↓ 4p ↑ ↓ ↑ ↓ ↑ ↓ 3d ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ 4s ↑ ↓ 3p ↑ ↓ ↑ ↓ ↑ ↓ 3s ↑ ↓ 2p ↑ ↓ ↑ ↓ ↑ ↓ 2s ↑ ↓ 1s ↑ ↓ (A) Mo (B) Tc (C) Mn (D) W (E) Ru BONUS: Which of the following species are isoelectronic with Krypton? (A) Br - (B) Sr 2+ (C) As 3- (D) None of the above (E) All of the above

KE = ½mv 2 ΔE = E prod – E reac ΔE sys = – ΔE sur q = m x C s x ΔT q = C x ΔT ΔH° rxn = Σ n·ΔH° f (products) - Σ n·ΔH° f (reactants) ν = c/λ E = hν E = (hc)/λ λ = h / mv E n =− 2.18 x 10 − 18 J 1 n 2 ∆ E =− 2.18 x 10 − 18 J ( 1 n f 2 − 1 n i 2 ) h = 6.626 x 10 -34 J·s c = 3.00 x 10 8 m/s

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