Adapted by Nelson Nuñez-Rodriguez
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By David W. Ball
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| QUESTION | ANSWER |
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1. Under what circumstances are q and ΔH the same? |
1. under conditions of constant pressure |
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3. Hydrogen gas and chlorine gas react to make hydrogen chloride gas with an accompanying enthalpy change of −184 kJ. Write a properly balanced thermochemical equation for this process. |
3. H2(g) + Cl2(g) → 2HCl(g) ΔH = −184 kJ |
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5. Nitrogen gas reacts with oxygen gas to make NO(g) while absorbing 180 kJ. Write a properly balanced thermochemical equation for this process. |
5. N2(g) + O2(g) → 2NO(g) ΔH = 180 kJ |
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7. Hydrogen gas and chlorine gas react to make hydrogen chloride gas with an accompanying enthalpy change of −184 kJ. Is this process endothermic or exothermic? |
7. exothermic |
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9. Nitrogen gas reacts with oxygen gas to make NO(g) while absorbing 180 kJ. Is this process exothermic or endothermic? |
9. endothermic |
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11. Draw an energy level diagram for the chemical reaction in Exercise 8. (See Figure 2.3 "Reaction Energy" for an example.) |
11. 
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13. In a 250 mL solution, 0.25 mol of KOH(aq) and 0.25 mol of HNO3(aq) are combined. The temperature of the solution increases from 22.5°C to 35.9°C. Assume the solution has the same density and heat capacity of water. What is the heat of the reaction, and what is the ΔH of the reaction on a molar basis? |
13. heat of reaction = −14.0 kJ; ΔH = −56.0 kJ/mol of reactants |
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15. To warm 400.0 g of H2O, 0.050 mol of ethanol (C2H5OH) is burned. The water warms from 24.6°C to 65.6°C. What is the heat of the reaction, and what is the ΔH of the reaction on a molar basis? |
15. heat of reaction = −68.6 kJ; ΔH = −1,370 kJ/mole of ethanol |