chapter-9_summary

In this summary, we covered various topics related to heat and thermodynamics: 1. The temperature of a substance burning (wood) remains approximately constant regardless of the amount, making it an intensive property. However, the total amount of heat produced increases with more material, due to the extensive nature of heat. 3. Heat capacity is the heat required to raise the temperature of a mass of a substance 1 degree, while specific heat is the heat required to raise the temperature of 1 gram of the substance 1 degree. 5. Specific heats for two substances were given: (a) 47.6 J/°C; 11.38 cal °C−1, (b) 407 J/°C; 97.3 cal °C−1. 7. The heat required for a process was calculated: 1310 J; 313 cal 9. The final temperature after a heat loss was found: 7.15 °C 11. The specific heats for two substances were identified as likely candidates: (a) 0.390 J/g °C (Copper is a likely candidate), (b) Water is a likely candidate. 13. The energy required for a given temperature change was calculated: 7.47 kWh 15. A lesser amount of heat would be transferred in a lesser insulated system. 17. Including the calorimeter in the calculations for the heat of a reaction will yield a greater value as it compensates for heat lost to the solution and the environment. 19. The temperature of the coffee will drop 1 degree. 21. Heat produced by a given reaction: 5.7 kJ 23. The boiling point of a substance was calculated: 38.5 °C 25. An exothermic reaction produces heat. 27. The change in temperature was calculated as less due to the increase in the amount of water. 29. The amount of HCl used was 0.24 g. 31. The enthalpy change for a reaction was calculated: 11.7 kJ 33. The percent yield was calculated: 30% 35. The mass of silver produced was calculated: 0.24 g 37. The heat required for a reaction was calculated: 1.4 × 102 Calories 39. The enthalpy change in the example was calculated: 25 kJ mol⁻¹ 41. The enthalpy change for a reaction was calculated: 81 kJ mol⁻¹ 43. The enthalpy change for a reaction was calculated: 5204.4 kJ 45. The amount of HCl needed was calculated: 1.83 × 10⁻² mol 47. The enthalpy change for a reaction was calculated: −802 kJ mol⁻¹ 49. The enthalpy change for a reaction was calculated: 15.5 kJ/ºC 51. The mass of sodium ions needed was calculated: 7.43 g 53. Yes, the substance has a melting point. 55. The enthalpy change for a reaction was calculated: 459.6 kJ 57. The enthalpy change for a reaction was calculated: −494 kJ/mol 59. The entropy change for a reaction was calculated: 44.01 kJ/mol 61. The enthalpy change for a reaction was calculated: −394 kJ 63. The enthalpy change for a reaction was calculated: 265 kJ 65. The enthalpy change for a reaction was calculated: 90.3 kJ/mol 67. The enthalpy change for a reaction was calculated: −1615.0 kJ mol⁻¹, −484.3 kJ mol⁻¹, 164.2 kJ, −232.1 kJ 69. The molarity of a solution was calculated as [H +] = 0.025 M. 71. The enthalpy change for a reaction was calculated: −54.04 kJ mol⁻¹ 73. The enthalpy change for a reaction was calculated: −2660 kJ mol⁻¹ 75. The enthalpy change for a reaction was calculated: −122.8 kJ 77. The mass of a substance needed was calculated as 3.7 kg. 81. Based on the assumption that the best rocket fuel is the one that gives off the most heat, B2H6 is the prime candidate. 83. The standard enthalpy change for a reaction was calculated: −88.2 kJ 85. (a) 1570 L air, (b) 75.4 °C, (c) −104.5 kJ mol⁻¹, (d) −114 kJ 88. (a) −114 kJ, (b) 30 kJ, (c) −1055 kJ