Ch 7 HW

A. 22.2°C B. -22.2°C C. 42.8°C D. -42.8°C E. None of these is within 5% of the correct answer

42.8°C

When 165 mL of water at 22°C is mixed with 85 mL of water at 82°C, what is the final temperature? (Assume that no heat is lost to the surroundings; d of water = 1.00 g/mL, specific heat capacity of water is 4.184 J/g.K) A. 42°C B. 52°C C. 61°C D. -61°C E. None of these is within 5% of the correct answer

42°C

A chunk of aluminum at 91.4°C was added to 200.0 g of water at 15.5°C. The specific heat of aluminum is 0.897 J/g°C, and the specific heat of water is 4.18 J/g°C. When the temperature stabilized, the temperature of the mixture was 18.9°C. Assuming no heat was lost to the surroundings, what was the mass of aluminum added? A. 243 g B. 34.7 g C. 41.7 g D. 43.7 g E. none of these

43.7 g

In a certain process, 750 J of work is done on a system which gives off 195 J of heat. The value of ΔE for the process is A. -555 J B. 750 J C. 555 J D. -195 J E. 195 J

555 J

Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II) oxide.2PbS(s) + 3O2(g) → 2PbO(s) + 2SO2(g), ΔH = -827.4 kJWhat mass of galena is converted to lead oxide if 975 kJ of heat are liberated? A. 203 g B. 282 g C. 406 g D. 478 g E. 564 g

564 g

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C in an insulated calorimeter? A. 35°C B. 42°C C. 53°C D. 58°C E. 70°C

58°C

A 28.5 g sample of metal X is heated to 95.0C and then dropped into 58.0 g of water in a coffee-cup calorimeter. The temperature of the water rises from 23.5 C to 27.1C. Calculate the specific heat of X. The specific heat capacity of water is 4.184 J/g.°C. A. 0.11 J g-1°C-1 B. 0.45 J g-1°C-1 C. 2.2 J g-1°C-1 D. 1.6 x 102 J g-1°C-1 E. 7.8 x 10-3 J g-1°C-1

0.45 J g-1°C-1

What is the specific heat capacity of a metal if it requires 176.9 J to change the temperature of 15.0 g of the metal from 25.00°C to 32.00°C? A. 11.8 J/g°C B. 25.3 J/g°C C. 282 J/g°C D. 1.68 J/g°C E. 0.594 J/g°C

1.68 J/g°C

What is the specific heat capacity of a metal if it requires 176.9 J to change the temperature of 15.0 g of the metal from 25.00°C to 32.00°C? A. 25.3 J/g°C B. 1.68 J/g°C C. 11.8 J/g°C D. 282 J/g°C E. 0.594 J/g°C

1.68 J/g°C

Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories? A. 1.92 × 10¯1 kcal B. 1.92 × 102 kcal C. 3.36 × 103 kcal D. 1.92 × 105 kcal E. 3.36 × 106 kcal

1.92 × 102 kcal

Using the information given below, calculate ΔHrxn for WO3(s) + 3H2(g) => W(s) + 3H2O(g) 2W(s) + 3O2(g) => 2WO3(s) ΔH = -1685 kJ 2H2(g) + O2(g) => 2H2O(g) ΔH = -477.84 kJ A. -252.9 kJ B. 252.9 kJ C. 125.9 kJ D. 364.9 kJ E. 1207.6 kJ

125.9 kJ

Calculate the energy change in kJ/mol for the reaction Li(g) + F(g) => Li+(g) + F-(g) (separated ions) using the following information: Li(g) → Li+(g) + e- +520 kJ/mol F(g) + e- → F-(g) -328 kJ/mol Enter your answer as the closest whole number with appropriate sign and without units.

192

Complete combustion of 1.0 metric ton of coal (assuming it to be pure carbon) to gaseous carbon dioxide releases 3.3 x 1010 J of heat. Convert this energy to kilojoules A. 3.3 x 107 kJ B. 3.3 x 1013 kJ C. 3.3 x 108 kJ D. 3.3 x 1012 kJ E. None of these is within 5% of the correct answer

3.3 x 107 kJ

Complete combustion of 1.0 metric ton of coal (assuming it to be pure carbon) to gaseous carbon dioxide releases 3.3 x 1010 J of heat. Convert this energy tokilojoules A. 3.3 x 107 kJ B. 3.3 x 1013 kJ C. 3.3 x 108 kJ D. 3.3 x 1012 kJ E. None of these is within 5% of the correct answer

3.3 x 107 kJ

How much heat is released when 192 g water is cooled from 54 degrees Celcius to 16 degrees Celcius? (specific heat of water = 4.184 J g-1°C-1) A. 1700 J B. 30,000 J C. -30,000 J D. 43,000 J E. 7300 J

30,000 J

A bomb calorimeter has a heat capacity of 783 J/oC and contains 254 g of water whose specific heat capacity is 4.184 J/goC. How much heat, in kilojoules, is evolved or absorbed by a reaction when the temperature goes from 23.73 oC to 26.01 oC? cH2O = 4.184 J/g.K A. 4200 kJ absorbed B. 2420 kJ absorbed C. 4.21 kJ evolved D. 2.42 kJ absorbed E. 1.78 kJ evolved

4.21 kJ evolved

What is the heat capacity of a metal slug if a temperature rise from 25C to 54C requires 135 J? A. 0.21 J/C B. 4.7 J/C C. 0.60 J/C D. 2.5 J/C E. -4.6 J/C

4.7 J/C

Which of the following has the bonds listed in the order of increasing bond energy? A. N≡N, N = N, N − N B. N≡N, N − N, N = N C. N − N, N = N, N≡N D. N = N, N − N, N≡N E. N = N, N≡N, N − N

N − N, N = N, N≡N

Using the bond energies provided below, calculate an estimate of ∆E for the reaction: CH4(g) + 2Cl2(g) → CH2Cl2(g) + 2HCl(g) Bond energies: C-H = 413 kJ/mol Cl-Cl = 243 kJ/mol C-Cl = 339 kJ/mol, H-Cl = 427 kJ/mol A. 1422 kJ B. 440 kJ C. 110 kJ D. -110 kJ E. None of these

None of these

Which of the following bonds is weakest? A. P-P B. P-F C. P-Cl D. P-Br E. P-I

P-I

NU There is a gas confined to a container with a moveable piston, where F is force acting on a piston of area A. Pressure is defined as forcer per unit area; thus the pressure of the gas is [formula]

P= F/A

Enthalpy: E is internal energy of the system, P is the pressure, and V is the volume. For a process carried out at constant pressure and only volume changes, (only work allowed is that from volume change) Enthalpy: how much energy was absorbed or released?

deltaH = DeltaE + PdeltaV

Classify the following processes as exothermic or endothermic freezing of water

exothermic

Pick the member of each pair with the greater bond energy. i) C-F or C-Cl ii) carbon-carbon bond in C2H4 or bond in F2 iii) C-O or C=O A. i) C-F ii) C2H4 iii) C=O B. i) C-F ii) F2 iii) C=O C. i) C-F ii) F2 iii) C-O D. i) C-Cl ii) C2H4 iii) C=O E. i) C-Cl ii) F2 iii) C-O

i) C-F ii) C2H4 iii) C=O

The __________ energy of a system is the sum of the kinetic and potential energies of all the particles in the system.

internal

Which of the following is both a greenhouse gas and a fuel? A. freon B. carbon dioxide C. nitrogen D. methane E. coal

methane

Estimate ΔE for the reaction: C2H6(g) + Cl2(g) ---> C2H5Cl(g) + HCl(g) given the following average bond energies in kJ/mol: C-C, 348; C-H, 414; Cl-Cl, 242; C-Cl, 327; H-Cl, 431 A. -113 kJ/mol B. -68 kJ/mol C. -102 kJ/mol D. -344 kJ/mol E. 276 kJ/mol

-102 kJ/mol

The thermite reaction, below, is highly exothermic. 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s), ΔH = -850 kJ What mass of iron is formed when 725 kJ of heat are released? A. 47 g B. 65 g C. 95 g D. 112 g E. 130 g

95 g

Estimate ΔE for the reaction: C2H6(g) + Cl2(g) ---> C2H5Cl(g) + HCl(g) given the following average bond energies in kJ/mol: C-C, 348; C-H, 414; Cl-Cl, 242; C-Cl, 327; H-Cl, 431 A. -113 kJ/mol B. -68 kJ/mol C. -102 kJ/mol D. -344 kJ/mol E. 276 kJ/mol

-102 kJ/mol

The combustion of 5.00 grams of C2H6(g), at constant pressure releases 259 kJ of heat. What is ΔH for the reaction: 2C2H6(g) + 7O2(g) => 4CO2(g) + 6H2O(l)? A. -259 kJ B. -518 kJ C. -1295 kJ D. -1554 kJ E. -3108 kJ

-3108 kJ

A gas does 189 J of work while expanding, and at the same time it absorbs 154 J of heat. What is the change in internal energy? A. -343 B. 35.0 C. -35.0 D. 29.1 E. 343

-35.0

Calculate q in J when 6.6 g of ice is cooled from -21.4°C to -97.8°C (cice = 2.087 J/g·K). Do not add units to your answer.

-1,052 ± 4%

A bomb calorimeter has a heat capacity of 2.47 kJ/K. When a 0.105 g sample of ethylene (C2H4) is combusted in this calorimeter, the temperature increases by 2.14 K. What is the heat of combustion per mole of ethylene? A. -5.29 kJ B. -50.3 kJ C. -572 kJ D. -661 kJ E. -1.41 x 103 kJ

-1.41 x 103 kJ

Data: 2Ba(s) + O2(g) => 2BaO(s) ΔH = -1107.0 kJ Ba(s) + CO2(g) + 1/2O2(g) => BaCO3(s) ΔH = -822.5 kJ Given the data above, calculate ΔH for the reaction below. Reaction: BaCO3(s) => BaO(s) + CO2(g) A. -1929.5 kJ B. -1376.0 kJ C. -284.5 kJ D. 269.0 kJ E. 537 kJ

269.0 kJ

Calculate H for the following reaction using the given enthalpies of formation. 2NO(g) + 5O2(g) -> 2NO2(g) deltaHfNO(g) = 90.25 kj/mol-1 deltaHfNO2(g) = 33.18 kj/mol-1 A. +57.07 kJ B. -57.07 kJ C. +114.14 kJ D. -114.14 kJ E. +66.36 kJ

-114.14 kJ

Add the following thermochemical equations: (1) P4(s) + 6Cl2(g) => 4PCl3(g) ΔH = -1148 kJ (2) 4PCl3(g) + 4Cl2(g) => 4PCl5(g) ΔH =-460 kJ (3) Overall equation = ? ΔH overall = ? Select the correct ΔH for the overall process (equation 3) A. -688 kJ B. 688 kJ C. -1608 kJ D. 1608 kJ E. None of these is within 5% of the correct answer

-1608 kJ

Calculate the work for the expansion of CO2 from 1.0 to 3.0 liters against a pressure of 1.0 atm at constant temperature. A. 3.0 L·atm B. 2.0 L·atm C. -3.0 L·atm D. -2.0 L·atm E. 0 L·atm

-2.0 L·atm

Given the information below calculate ΔH°rxn for: C2H4(g) + 6F2(g) => 2CF4 + 4HF(g) H2(g) + F2(g) => 2HF(g) ΔH° = -537 kJ C(s) + 2F2(g) => CF4(g) Δ°H = -680 kJ 2C(s) + 2H2(g) => C2H4(g) ΔH° = 52.3 kJ A. -1165 kJ B. -1269 C. -2382 kJ D. -2486 kJ E. -1642 kJ

-2486 kJ

Calculate the energy change (ΔE) for the reaction below, N2(g) + 3 F2(g) → 2 NF3(g) given these bond energies of the reactants and products. Ν−N =163 N=N = 418 Ν.N = 945 F −F = 155 Ν−F = 283 A. -288 kJ B. -1070 kJ C. -637 kJ D. +288 kJ E. +293 kJ

-288 kJ

A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of 0.500 M HCl at 25.0°C is added to 50.0 mL of 0.500 M NaOH at 25.0°C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2°C. What is the heat of reaction per mole of acid? Assume the mixture has a specific heat capacity of 4.18 J/(g ∙ K) and that the densities of the reactant solutions are both 1.00 g/mL. A. -670 J B. -1300 J C. -27 kJ D. -54 kJ E. < -100 kJ

-54 kJ

When 40.0 mL of 0.200 M HCl at 21.5°C is added to 40.0 mL of 0.200 M NaOH also at 21.5°C in a coffee-cup calorimeter, the temperature of the resulting solution rises to 22.8°C. Assume that the volumes are additive, the specific heat of the solution is 4.18 Jg-1°C-1 and that the density of the solution is 1.00 g mL-1 Calculate the enthalpy change, ΔH in kJ for the reaction: HCl(aq) + NaOH(aq) => NaCl(aq) + H2O(l) A. -54.3 kJ B. -435 kJ C. +21.5 kJ D. +48.6 kJ E. +435 kJ

-54.3 kJ

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 ΔH for the reaction as represented by the equation below. 2CO(g) + O2(g) => 2CO2 A. -566 kJ B. -283 kJ C. 283 kJ D. 141 kJ E. -141 kJ

-566 kJ

How much heat flows (in J) when a 29.0 gram block of metal changes temperature from 15 ºC to 72 ºC?The specific heat of the metal is 0.424 J/g•ºC. A. 700 B. -24 C. -3900 D. -1700 E. -700

-700

Use the given average bond dissociation energies to estimate ΔE (kJ) for the reaction of methane, CH4(g), with fluorine according to the equation below. Enter your answer as the nearest whole number without units. CH4(g) + 2 F2(g) → CF4(g) + 2 H2(g) C-F -> 450 C-H -> 410 F-F -> 158 H-H -> 436

-716

Data: ΔHf values: CH4(g), -74.8 kJ; CO2(g), -393.5 kJ; H2O(l), -285.8 kJ. Using the ΔHf data above, calculate ΔHrxn for the reaction below. Reaction: CH4(g) + 2O2(g) => CO2(g) + 2H2O(l) A. -604.2 kJ B. 890.3 kJ C. -997.7 kJ D. -890.3 kJ E. none of the above

-890.3 kJ

One step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) Calculate ΔH°rxn for this reaction. ΔH°f [NH3(g)] = -45.9 kJ/mol; ΔH°f [NO(g)] = 90.3 kJ/mol; ΔH°f [H2O(g)] = -241.8 kJ/mol. A. -906.0 kJ B. -197.4 kJ C. -105.6 kJ D. 197.4 kJ E. 906.0 kJ

-906.0 kJ

The compound carbon suboxide, C3O2, is a gas at room temperature. Use the data supplied to calculate the heat of formation of carbon suboxide. (Data: 2CO(g) + C(s) → C3O2(g), ΔH° = 127.3 kJ/mol and ΔH°f of CO(g) = -110.5 kJ/mol) A. 116.8 B. -93.7 C. 227.8 D. -348.3 E. 93.7

-93.7

What is the final temperature of a 52 gram glass of water at 2.0 C if it absorbs 3.0 J heat? A. -2.0 B. -210 C. 150 D. 2.0 E. 75

2.0

If the heat capacity of a ceramic cup is 0.820 J°C-1, how much heat is required to raise the temperature of the cup from 25.0°C to 50.0°C? A. 82.0 J B. 20.5 J C. 41.0 J D. 50.0 J E. 61.0 J

20.5 J

A mercury mirror forms inside a test tube by the thermal decomposition of mercury(II) oxide: 2HgO(s) => 2Hg(l) + O2(g) ΔHrxn = 181.6 kJ How much heat is needed to decompose 555 g of the oxide? A. 233 kJ B. -233 kJ C. 465 kJ D. -465 kJ E. 23.3 kJ

233 kJ

A. 1.52 x 103 kJ B. 7.58 kJ C. 90.1 kJ D. 35.3 kJ E. 128 kJ

7.58 kJ/C

Perform the indicated conversion: 31.95 kJ = _______________ kcal A. 0.1310 kcal B. 7.636 kcal C. 7.636 x 103 kcal D. 1.337 x 102 kcal E. 13.37 x 10-2 kcal

7.636 kcal

Complete combustion of 1.0 metric ton of coal (assuming pure carbon) to gaseous carbon dioxide releases 3.3 x 1010 J of heat. Convert this energy to kilocalories A. 7.9 x 109 kcal B. 1.4 x 108 kcal C. 7.9 x 106 kcal D. 1.4 x 1011 kcal E. None of these is within 5% of the correct answer

7.9 x 106 kcal

A 15.0 g block of aluminum at an initial temperature of 27.5C absorbs 0.678 kJ of heat. What is the final temperature of the block? The specific heat of Al is 0.902 J g-1°C-1. A. 50.1C B. 38.6C C. 54.5C D. 68.6C E. 77.6C

77.6C

One piece of copper jewelry at 105°C has exactly twice the mass of another piece, which is at 45°C. Both pieces are placed inside a calorimeter whose heat capacity is negligible. What is the final temperature inside the calorimeter (c of copper = 0.387 J/g·K)? A. 23.2°C B. 85.0°C C. 55.0°C D. 65°C E. None of these is within 5% of the correct answer

85.0°C

Thermal decomposition of rail car load of limestone to lime and carbon dioxide requires 5.74 x 106 kJ of heat. Convert this energy to calories. Once you have the value, determine its log (base 10) and enter this in decimal format with three decimal places. Do not include units.

9.137 ± 0.05

How much heat, in Joules, must be added to 11 grams water in order to raise the temperature from 17 to 45? A. 1300 B. 310 C. 120 D. 780 E. -1300

A. 1300

Choose the correct equation for the standard enthalpy of formation of CO(g), where ΔHf° for CO = -110.5 kJ/mol (gr indicates graphite). A. CO(g) → C(gr) + O(g), ΔH° = -110.5 kJ B. 2C(gr) + O2(g) → 2CO(g), ΔH° = -110.5 kJ C. C(gr) + CO2(g) → 2CO(g), ΔH° = -110.5 kJ D. C(gr) + O2(g) → CO(g), ΔH° = -110.5 kJ E. C(gr) + O(g) → CO(g), ΔH° = -110.5 kJ

C(gr) + O2(g) → CO(g), ΔH° = -110.5 kJ

Which of the following is in the order of decreasing bond strength? A. Cl − Cl, I − I, Br − Br B. Br − Br, Cl − Cl, I − I C. I − I, Br − Br, Cl − Cl D. Cl − Cl, Br − Br, I − I E. I − I, Cl − Cl, Br − Br

Cl − Cl, Br − Br, I − I

Predict which of the following bonds has the smallest bond energy. A. C-Cl B. C-C C. C=C D. C=O E. Cl-Cl

Cl-Cl

The internal energy of a system can be changed by a flow of work, heat, or both. That is, [formula], where delta E represents the change in the system's internal energy, q represents heat, and w represents work.

DeltaE = q + w

n which of the following processes is ΔH = ΔE ? A. Two moles of ammonia gas are cooled from 325°C to 300°C at 1.2 atm. B. One gram of water is vaporized at 100°C and 1 atm. C. Two moles of hydrogen iodide gas react to form hydrogen gas and iodine gas in a 40-L container. D. Calcium carbonate is heated to form calcium oxide and carbon dioxide in a container with variable volume. E. One mole of solid carbon dioxide sublimes to the gas phase.

Two moles of hydrogen iodide gas react to form hydrogen gas and iodine gas in a 40-L container.

[ Constant Pressure Calorimetry] We have found that when an object changes temperature, the heat can be calculated from the equation [formula] where s is specific heat compacity, m is the mass, and deltaT is change in temperature

q = s*m*deltaT

This formula gives the magnitude of work required to expand a gas (deltaV) against a pressure P.

w = -P*deltaV

For a particular process q = 20 kJ and w = 15 kJ. Which of the following statements is true? A. Heat flows from the system to the surroundings. B. The system does work on the surroundings. C. ΔE = 35 kJ D. All of the above are true. E. None of the above are true.

ΔE = 35 kJ