wrksht6key - DZ “asm‘m Poke.“ Pl“st {9:43 Chemistry...

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Unformatted text preview: DZ “asm‘m Poke.“ Pl“st {9:43 Chemistry 210 Chapter 6: Thermochemistry Worksheet 6 Please answer all questions in the spaces provided. 1. An electron whose mass is 9.11 x 10'31 kg is accelerated to a speed of 5.0 x 106 m/s. What is the kinetic energy of the electron in joules ? 1 J = 1 kg m2/s2 \:_ 1::— J2'; MVL E 2 J2: Gil“ :uO-‘S‘K )G'CX‘Q‘MJZ :3 s 3's? ‘ 2. 2A928 (s) + 2H20 (I) —> 4Ag (s) + 2HZS(g) + 02 (9) AH = +5955 kJ Given the equation above, calculate AH for the following reaction: - $93-$10) . , Ag (s)+ %H28(g)+ £02 (g>—> %A923 (s)+ $4420 (I) Maj—1 -‘-’ Ma“ The next two questions refer to the following equation: 2 NH3(g) + 3N20(g) -) 4N2(g) + 3H20(l) AH = -1010 kJ 3. What quantity of heat is liberated when 50.0 g of N20 (9) reacts with excess NH3(Q) ? t M N10 — x 30-03qu x x "now =\“ 3‘53 Li'Lk ’5 “N 7,0 4. How many grams of NH3 must be reacted with excess N20 in order to liberate 2.5 x104 kJ of heat ? Worksheet 6 Answer Ke 6. Calculate the heat capacity of a sample of brake fluid if the sample must absorb 911 J of heat in order for its temperature to rise from 15 °C to 100 °C. ‘C: :MgnT (100°C ~Ls°c) cc. 7. What is the specific heat of ethyl alcohol if 129 J of heat is required to raise the temperature of 15.0 g of ethyl alcohol from 22.70 °C to 26.20 °C ? iii-LMXSXB'T/z %=_GV> :: ‘23: . 2' Z-H‘é 5' (M xbbB (IS‘O¢)C5.SOC_> soc 8. A piece of silver of mass 362 g has a heat capacity of 85.7 J/°C. What is the specific heat of silver ? s2;- : (as-+3.. . °C- 20.23%: i 3°C m 9. The specific heat of nickel is 0.444 J/g °C. lf 50.0 J of heat is added to a 32.39 sample of nickel at 23.3 °C, what is the final temperature of the sample? “VZM‘LS xb‘b Ab:.°V..——- =‘go'dzfl 2.35.21 M s L21.3&G,WWLEZ‘ - Age 0 \— btz'bgm- bmsmi, +4“ 2 No.4, «mm. 3 :- 23.3”(1-1—355 3 6.1;? 10. How much heat, in joules and kilojoules, does it take to raise the temperature of 814 g of water from 18.0 °C to 100.0 °C ? 11. The standard heat of formation of nitric acid, HN03(aq) is AH°f = —207.4 kJ/mol. Which equation is associated with this value ? a. H(g) + N(g) + 03(9) —> HN03 (aq) %H2(g) + %N2 (9) + %02 (g) 9 HNOs(aq) HNO3 (aq) 9 %H2 (9) + W (9) + %02(g) HNOs (3(1) ‘9 H(Q) + N(9) + 3 0(9) H2(9) + N2(Q) + 03(9) 9HN03(aq) Answer: B 99.0 Worksheet 6 Answer Key 12. Suppose 0.562 g of graphite is placed in a calorimeter with an excess of oxygen at 25.00 °C and 1 atm. Excess 02 ensures that all carbon burns to form C02. The graphite is ignited, and it burns according to the equation: C(graphite) + 02(9) ‘9 C02(9) On reaction, the calorimeter temperature rises from 25.00 °C to 25.89 °C. The heat capacity of the calorimeter and its contents was determined in a separate experiment to be 20.7 kJ/°C. What is the heat of reaction at 25.00 °C and 1 atm pressure ? Express the answer as a thermochemical equation. ccAQt‘wve‘t-er m‘d‘xk m’efl’ts: Wm L: 3 XCLS‘. 8‘1 °C. 41903 C cc ‘ ' * “7—3539: x 034°C- :s’nfis \S a: For\mo\ Q, 3 m0\cegc._9\£$ 0.367.3C._ 13. Suppose 33 mL of 1.20 M HCl is added to 42 mL of a solution containing excess sodium hydroxide, NaOH, in a coffee—cup calorimeter. The solution temperature, originally 25.0 °C. rises to 31.8 °C. Give the enthalpy change, AH, for the reaction: HCI(aq) + NaOH(aq) 9 NaCl(aq) + H20(I) Express the answer as a thermochemical equation. For simplicity, assume the heat capacity and density of the final solution in the cup are those of water (4.184 J/g °C and 1.00 g/mL, respectively). Also assume the total volume of the solution equals the sum of the volumes of HCI(aq) and NaOH(aq). Mm = «a = * Cm M m Notes 2 ate-swig x \lo\\Lfi‘Q_ msso§ schflm‘m :: V05 - \ x?S‘ \_ ._ C=ms C. :: q-ST’Z/x LbfiSH—S -—_~_ 3.1Lk2dO'LHS fc. °C.. 59mm 9: 33ml. a. i-‘LOH HQ ’2. bflnm = “'ch NC: = "3-lerK3 15: x @\.8—2S-0)°c. : *2“qu cc, To {Rod bfinpn) AM\DQ:\\=M\ HC\ ‘m 33mL%_ ].’2,QHHQ\ W 0.631%); \fLC) mat fit) 1 o~ogqua\ HQS l 25PM“ n: w _ (5H 7‘ o . 03%: um um ” HC‘ED‘F N¢OHG~J$Nm®u fHLOQ.) {Ly Worksheet 6 Answer Ke 14. From the standard enthalpies of formation listed below, calculate the AH° for the reaction: CeH12 (I) + 9 02 (g) -> 6 002 (g) + 6 H20 (l) AHf° (002 (9)) = -394 kJ/mol, [st0 (H20 (l)) = -286 kJ/mol AHf° (CeH12 (I)) = -152 kJ/mol AH? (02 (9)) = o kJ/mol Aw : 2 bagfimamg .. Z 13H; 663mm) 15. Calculate the enthalpy change for the reaction CzH4(9) + H2(9) 9 CZH6(9) AH = 7 given the following data: C2H4(g) + 302(g) -> 2002(9) + 2H20(l) AH = -1410.9 kJ 202H5(g) + 702(9) 9 4C02(g) + 6H20(l) AH = -3119.4 kJ 2H2(g) + 02(9) 9 2H20(l) AH = -571.6 kJ AH CszCQ) +/3>'©/1~Cs) —> 2/6267- Cts) + 2346(1) -—|lvl-l.0.<\ us- 1%1Q)+3MQ39C1‘H5(3)+ jag/2G3) +\S'bO £5" Hat‘s) + C3) ‘9 “35% *Zas‘g “3 €431)me + H1652 "fi C29“: (is) “ ‘3? WT ...
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This note was uploaded on 04/07/2008 for the course CHM 210 taught by Professor Patell during the Spring '08 term at Kansas State University.

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wrksht6key - DZ “asm‘m Poke.“ Pl“st {9:43 Chemistry...

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