(a) Using the heat of vaporization in Appendix B, calculate the e...

Question

(a) Using the heat of vaporization in Appendix B, calculate the entropy change for the vaporization of water at 25 °C and at 100 °C. (b) From your knowledge of microstates and the structure of liquid water, explain the difference in these two values.

Accepted Answer

Step 1: Identify the formula for entropy change during vaporization. The entropy change ($ \Delta S $) for vaporization can be calculated using the formula $ \Delta S = \frac{\Delta H_{vap}}{T} $, where $ \Delta H_{vap} $ is the heat of vaporization and $ T $ is the temperature in Kelvin.. Step 2: Convert the given temperatures from Celsius to Kelvin. Remember that the conversion is $ T(K) = T(°C) + 273.15 $. So, convert 25 °C and 100 °C to Kelvin.. Step 3: Look up the heat of vaporization ($ \Delta H_{vap} $) for water from Appendix B. This value is typically given in kJ/mol.. Step 4: Calculate the entropy change ($ \Delta S $) for each temperature using the formula from Step 1. Substitute the values of $ \Delta H_{vap} $ and the converted temperatures into the formula.. Step 5: Discuss the difference in entropy changes at 25 °C and 100 °C. Consider the concept of microstates and the structure of liquid water. At higher temperatures, molecules have more energy and more accessible microstates, leading to a greater increase in entropy upon vaporization.