Cooling the Steam
What mass of steam initially at 130oC is needed to warm 200 g of water in a 100-g glass container from 21.0oC to 47.0oC?
Conceptualize Imagine placing water and steam together in a closed insulated container. The system eventually reaches a uniform state of water with a final temperature of 47.0oC.
Categorize Based on our conceptualization of this situation, we categorize this example as one involving calorimetry in which a phase change occurs. The calorimeter is an isolated system for energy: energy transfers between the components of the system but does not cross the boundary between the system and the environment.
Write an equation to describe the calorimetry process:
The steam undergoes three processes: a decrease in temperature to 100oC, condensation into liquid water, and finally a decrease in temperature of the water to 47.0oC. Find the energy transfer in the first process using the unknown mass ms of the steam:
Find the energy transfer in the second process:
Find the energy transfer in the third process:
Add the energy transfers in these three stages:
The 21.0oC water and the glass undergo only one process, an increase in temperature to 47.0oC. Find the energy transfer in this process.