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Posted: Tue Jan 29, 2019 3:02 pm
In melting and boiling, why does the temperature of a sample stay constant even though heat is being added?
Posted: Tue Jan 29, 2019 3:04 pm
Hi! During a phase change, the temperature remains constant because the heat added is going to the phase change reaction itself, not towards the temperature. In other words, all of the heat energy is being used to change the phase of the substance. I hope that helps!
Posted: Tue Jan 29, 2019 3:14 pm
The temperature doesn't change because a phase change is happening. The heat being put into the system is causing the phase change and causing the molecules to overcome all the attractive forces, which allows a substance to go from solid to liquid and a liquid to a gas.
Posted: Tue Jan 29, 2019 3:30 pm
Also, it is helpful to recall the graph Professor Lavelle showed during lecture that shows that the added heat is contributing to the phase change and not raising the temperature. Like said above, the energy added is going into the phase change reaction. This added heat can also be observed when discussing why steam causes worse burns than boiling water at 100 degrees Celsius.