InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Calculate the standard enthalpy change for the reaction2C8H18(l) + 21O2(g) → 8CO(g) + 8CO2(g) + 18H2O(l). Given: 2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH° = –11,020 kJ/mol2CO(g) + O2(g) → 2CO2(g) ΔH° = –566.0 kJ/mol(A) 1.0454 x 104 kJ/mol(B) –8,756 kJ/mol(C) 1.1586 x 104 kJ/mol(D) –6,492 kJ/mol (E) –1.0454 ´ 104 kJ/mol |
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Answer» (B) –8,756 kJ/mol |
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| 2. |
The combustion of butane produces heat according to the equation 2C4H10(g) + 13O2(g) →8CO2(g) + 10H2O(l) ΔH°rxn= –5,314 kJ/mol How many grams of butane must be burned to release 1.00 x 104 kJ of heat?(A) 30.9 g (B) 61.8 g (C) 109 g (D) 153 g (E) 219 g |
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Answer» The Correct option is (E) 219 g |
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| 3. |
The combustion of butane produces heat according to the equation 2C4H10(g) + 13O2(g) → 8CO2(g) + 10H2O(l) ΔH°rxn = –5,314 kJ/mol What is the heat of combustion per gram of butane?(A) –32.5 kJ/g(B) –45.7 kJ/g(C) –91.5 kJ/g(D) –2,656 kJ/g(E) –15,440 kJ/g |
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Answer» (B) –45.7 kJ/g |
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| 4. |
For which of these reactions will the difference between ΔH° and ΔE° be the smallest? (A) N2(g) + 3H2(g) → 2NH3(g) (B) 4PH3(g) → P4(g) + 6H2(g) (C) H2(g) + Cl2(g) → 2HCl(g) (D) CO2(g) + 2H2O(l) → CH4(g) + 2O2(g) (E) P4(s) + 10Cl2(g) → 4PCl5(s) |
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Answer» (C) H2(g) + Cl2(g)→ 2HCl(g) |
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| 5. |
Methanol (CH3OH) burns according to the equation2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(l), ΔH°rxn = –1454 kJ/mol.How much heat, in kilojoules, is given off when 75.0 g of methanol is burned?(A) 727 kJ(B) 3.22 x 103 kJ(C) 1.45 x 103 kJ(D) 1.70 x 10–3 kJ(E) 3.41 x 103 kJ |
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Answer» (D) 1.70 x 10–3 kJ |
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| 6. |
For the reactionC(graphite) + O2(g) → CO2(g) ΔH° = –393 kJ/molHow many grams of C(graphite) must be burned to release 275 kJ of heat?(A) 22.3 g (B) 0.70 g (C) 12.0 g (D) 17.1 g (E) 8.40 g |
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Answer» The Correct option is (E) 8.40 g |
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| 7. |
At 25°C, the following heats of reaction are known: 2ClF(g) + O2(g) → Cl2O(g) + F2O(g ΔH°rxn = 167.4 kJ/mol2ClF3(g) + 2O2(g) → Cl2O(g) + 3F2O(g) ΔH°rxn = 341.4 kJ/mol2F2(g) + O2(g) → 2F2O(g) ΔH°rxn = –43.4 kJ/molAt the same temperature, use Hess's law to calculate ΔH°rxn for the reaction:ClF(g) + F2(g) → ClF3(g)(A) –217.5 kJ/mol(B) –130.2 kJ/mol(C) 217.5 kJ/mol(D) –108.7 kJ/mol |
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Answer» (D) –108.7 kJ/mol |
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| 8. |
Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l). Calculate ΔH°rxn for the combustion of 1 mol of B5H9. ΔH°f[B2O3(s)] = –1,273.5 kJ/mol ΔH°f[B5H9(s)] = 73.2 kJ/mol ΔH°f[H2O(l)] = –285.8 kJ/mol(A) –1,2735 kJ/mol(B) –4,543 kJ/mol(C) –18,170 kJ/mol(D) –9,086 kJ/mol(E) –8,448 kJ/mol |
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Answer» (B) –4,543 kJ/mol |
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| 9. |
Given the thermochemical equation 2SO2(g) + O2(g) → 2SO3(g), ΔH°rxn= –198 kJ/mol, how much heat is evolved when 600. g of SO2 is burned?(A) 5.46 x 10–2 kJ(B) 928 kJ(C) 1.85 x 103 kJ(D) 59,400 kJ(E) 3.71 x 103 kJ |
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Answer» The Correct option is (B) 928 kJ |
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| 10. |
Given that CaO(s) + H2O(l) →Ca(OH)2(s), ΔH°rxn = –64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat? (A) 6.92 g (B) 56.1 g (C) 455 g (D) 606 g (E) 3.40 x 104 g |
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Answer» The Correct option is (C) 455 g |
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| 11. |
10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H2O at 18.0°C. If the following reaction occurs, then what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat? (the specific heat of water = 4.18 J/g·°C)CaO(s) + H2O(l) → Ca(OH)2(s) ΔH°rxn = –64.8 kJ/mol(A) 18.02°C (B) 35.8°C (C) 311°C (D) 42.2°C (E) 117°C |
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Answer» The Correct option is (B) 35.8°C |
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| 12. |
At 25°C, the standard enthalpy of formation of KCl(s) is –435.87 kJ/mol. When one mole of KCl(s) is formed by reacting potassium vapor and chlorine gas at 25°C, the standard enthalpy of reaction is –525.86 kJ/mol. Find ΔH° for the sublimation of potassium, K(s) → K(g), at 25°C(A) –345.88 kJ/mol(B) 45.00 kJ/mol(C) 345.88 kJ/mol(D) 89.99 kJ/mol(E) –525.86 kJ/mol |
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Answer» (D) 89.99 kJ/mol |
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| 13. |
At 25°C, the standard enthalpy of formation of anhydrous sodium carbonate is –1130.9 kJ/mol, whereas the standard enthalpy of formation of sodium carbonate monohydrate is –1430.1 kJ/mol. Determine ΔH° at 25°C for the reactionNa2CO3(s) + H2O(l) → Na2CO3·H2O(s).(Given: ΔH°f[H2O(l)] = –285.8 kJ/mol)(A) –13.4 kJ/mol(B) –285.8 kJ/mol(C) –585.0 kJ/mol(D) –299.2 kJ/mol(E) –156.3 kJ/mol |
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Answer» (A) –13.4 kJ/mol |
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| 14. |
Calculate the amount of work done, in joules, when 2.5 mole of H2O vaporizes at 1.0 atm and 25°C. Assume the volume of liquid H2O is negligible compared to that of vapor. (1 L·atm = 101.3 J) (A) 6,190 kJ (B) 6.19 kJ (C) 61.1 J (D) 5.66 kJ (E) 518 J |
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Answer» The Correct option is (B) 6.19 kJ |
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| 15. |
To which one of the following reactions occurring at 25°C does the symbol ΔH°f[HNO3(l)] refer?(A) H(g) + N(g) + O3(g) → HNO3(l) (B) (1/2)H2(g) + (1/2)N2(g) + (3/2)O2(g) → HNO3(l) (C) HNO3(l) → (1/2)H2(g) + (1/2)N2(g) + (3/2)O2(g) (D) HNO3(l) → H(g) + N(g) + 3O(g) (E) H2(g) + N2(g) + O3(g) → HNO3(l) |
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Answer» (B) (1/2)H2(g) + (1/2)N2(g) + (3/2)O2(g) → HNO3(l) |
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| 16. |
When 18.5 g of HgO(s) is decomposed to form Hg(l) and O2(g), 7.75 kJ of heat is absorbed at standard-state conditions. What is the standard enthalpy of formation (ΔH°f) of HgO(s)?(A) –90.7 kJ/mol(B) –7.75 kJ/mol(C) 0.419 kJ/mol(D) 27.9 kJ/mol(E) 143 kJ/mol |
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Answer» (A) –90.7 kJ/mol |
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| 17. |
When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH°f) of NaF(s)?(A) 24.8 kJ/mol(B) 570 kJ/mol(C) –24.8 kJ/mol(D) –7.8 kJ/mol(E) -570 kJ/mol |
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Answer» (E) -570 kJ/mol |
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| 18. |
A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/°C. If the temperature rise of the calorimeter with water was 0.570°C, calculate the enthalpy of combustion of magnesium.Mg(s) + 1/2O2(g) → MgO(s)(A) –3280 kJ/mol(B) –24.8 kJ/mol(C) 435 kJ/mol(D) 106 kJ/mol(E) –602 kJ/mol |
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Answer» (E) –602 kJ/mol |
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| 19. |
Define specific heat. |
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Answer» The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. |
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| 20. |
Which of the following processes is endothermic? (A) O2(g) + 2H2(g) → 2H2O(g) (B) H2O(g) → H2O(l) (C) 3O2(g) + 2CH3OH(g) → 2CO2(g) + 2H2O(g) (D) H2O(s) → H2O(l) |
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Answer» (D) H2O(s) → H2O(l) |
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| 21. |
Find the heat absorbed from the surroundings when 15 g of O2 reacts according to the equation O + O2 → O3, ΔH°rxn= –103 kJ/mol. (A) 4.6 x 10–3 kJ (B) 48 kJ (C) 96 kJ (D) 32 kJ (E) 110 kJ |
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Answer» The Correct option is (B) 48 kJ |
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| 22. |
The heat of solution of ammonium nitrate is 26.2 kJ/mol. If a 5.368 g sample of NH4NO3 is added to 40.0 mL of water in a calorimeter at 23.5°C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 650. J/°C.) (A) 14.3°C (B) 20.8°C (C) –7.7°C (D) 25.6°C (E) 21.4°C |
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Answer» The Correct option is (E) 21.4°C |
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| 23. |
A glass containing 200. g of H2O at 20°C was placed in a refrigerator. The water loses 11.7 kJ as it cools to a constant temperature. What is its new temperature? The specific heat of water is 4.184 J/g·°C. (A) 0.013°C (B) 4°C (C) 6°C (D) 14°C (E) 34°C |
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Answer» The Correct option is (C) 6°C |
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| 24. |
If 325 g of water at 4.2°C absorbs 12.28 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/g·°C. (A) 4.21°C (B) 4.8°C (C) 9.0°C (D) 13.2°C (E) 2,938°C |
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Answer» The Correct option is (D) 13.2°C |
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| 25. |
Aluminum oxide can be reduced to aluminum metal using carbon, the other reaction product being carbon monoxide. Determine the enthalpy change when 12.5 g of aluminum is produced by this method. [ΔH°f(carbon monoxide) = –110.5 kJ/mol; ΔH°f(aluminum oxide) = –1669.8 kJ/mol] (A) 725 kJ (B) 697 kJ (C) 310 kJ (D) 361 kJ (E) 1504 kJ |
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Answer» The Correct option is (C) 310 kJ |
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| 26. |
How many degrees of temperature rise will occur when a 25.0 g block of aluminum absorbs 10.0 kJ of heat? The specific heat of Al is 0.900 J/g·°C. (A) 0.44°C (B) 22.5°C (C) 225°C (D) 360°C (E) 444°C |
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Answer» The Correct option is (E) 444°C |
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| 27. |
The specific heat of gold is 0.129 J/g·°C. What is the molar heat capacity of gold?(A) 0.039 J/mol·°C(B) 0.129 J/mol·°C(C) 25.4 J/mol·°C(D) 39.0 kJ/mol·°C(E) 197 J/mol·°C |
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Answer» (C) 25.4 J/mol·°C |
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| 28. |
Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g·°C) at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks (A) will be higher than 50°C. (B) will be lower than 50°C. (C) will be exactly 50°C. (D) is unrelated to the composition of the blocks. (E) cannot be predicted. |
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Answer» (B) will be lower than 50°C. |
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| 29. |
An endothermic reaction causes the surroundings to (A) warm up. (B) become acidic(C) condense.(D) decrease in temperature.(E) release CO2. |
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Answer» (D) decrease in temperature. |
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| 30. |
Copper metal has a specific heat of 0.385 J/g·°C. Calculate the amount of heat required to raise the temperature of 22.8 g of Cu from 20.0°C to 875°C. (A) 1.97 x 10–5 J (B) 1.0 x 10–2 J (C) 329 J (D) 7.51 kJ (E) 10.5 kJ |
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Answer» (D) 7.51 kJ. |
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| 31. |
How much heat is required to raise the temperature of 2,500 g of water from 27°C to 72°C? The specific heat of water is 4.184 J/g·°C. (A) 0.19 kJ (B) 10. kJ (C) 280 kJ (D) 470 kJ (E) 750 kJ |
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Answer» The Correct option is (D) 470 kJ. |
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| 32. |
the enthalpy change for the reaction C3H8 + H2 =C2H6 + CH4 at 25*c is 55.7 kj/mole Calculate the heat of combusition of C2H6 .the heat of combustion of H2.CH4,C[graphite] are -285.8 , -890.0 , -393.5 kj/mole respestevily . Heat of combustion of propani is -2240 kj/mole |
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Answer» Given C3H8 + H2 =C2H6 + CH4, ΔH1= + 55.7 kJ/mole H2+1/2O2 =H2O, ΔH2= -285.8 kJ/mole CH4+2O2 =CO2+2H2O, ΔH3= -890.0 kJ/mole C(graphite)+O2 =CO2, ΔH4= -393.5 kJ/mole C3H8 +5 O2 =3 CO2+4H2O, ΔH5= -2240 kJ/mole we are to measure C2H6 +7/2 O2 =2CO2+3H2O, ΔH6= ? kJ/mole So ΔH6 = ΔH5- ΔH1 + ΔH2 - ΔH3 = -2240- 55.7 + (-285.8) -(-890.0) = -1691.5 kJ/mole
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| 33. |
Styrene, C8H8, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25°C, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C.(Given: ΔH°f[CO2(g)] = –393.5 kJ/mol, ΔH°f[H2O(l)] = –285.8 kJ/mol, ΔH°f[H2O(g)] = –241.8 kJ/mol)(A) 323.8 kJ/mol (B) ~4249 kJ/mol(C) ~8730 kJ/mol(D) ~636.7 kJ/mol(E) 147.8 kJ/mol |
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Answer» (E) 147.8 kJ/mol |
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| 34. |
Glycine, C2H5O2N, is important for biological energy. The combustion reaction of glycine is given by the equation4C2H5O2N(s) + 9O2(g) →8CO2(g) + 10H2O(l) + 2N2(g) ΔH°rxn = –3857 kJ/molGiven that DH°f[CO2(g)] = –393.5 kJ/mol and ΔH°f[H2O(l)] = –285.8 kJ/mol, calculate the enthalpy of formation of glycine.(A) –537.2 kJ/mol(B) –268.2 kJ/mol(C) 2,149 kJ/mol(D) –3,178 kJ/mol(E) –964 kJ/mol |
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Answer» (A) –537.2 kJ/mol |
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| 35. |
Octane (C8H18) undergoes combustion according to the following thermochemical equation:2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH°rxn = –11,020 kJ/molGiven that Δ H°f[CO2(g)] = –393.5 kJ/mol and ΔH°f[H2O(l)] = –285.8 kJ/mol, calculate the standard enthalpy of formation of octane.(A) –210 kJ/mol(B) –11,230 kJ/mol(C) 22,040 kJ/mol(D) –420 kJ/mol(E) 420 kJ/mol |
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Answer» (A) –210 kJ/mol |
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| 36. |
Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: heat of combustion of C2H4(g) = –1411 kJ/mol; ΔH°f[CO2(g)] = –393.5 kJ/mol; ΔH°f[H2O(l)] = –285.8 kJ/mol.(A) 52 kJ/mol(B) 87 kJ/mol(C) 731 kJ/mol(D) 1.41 x 103 kJ/mol(E) 2.77 x 103 kJ/mol |
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Answer» (A) 52 kJ/mol. |
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