## Heating Curve

$\Delta U=q+w$

ntruong2H
Posts: 50
Joined: Sat Jul 09, 2016 3:00 am
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### Heating Curve

Why is it that although heat is being added at a sample's melting and boiling points, the temperature remains constant and the curve therefore looks flat? I thought that since heat is being added that the temperature would increase and the graph thus would have an increasing slope? Similarly, can someone explain why the curve is increasing in between the different phase states?

Christopher Liu 3J
Posts: 20
Joined: Fri Jul 15, 2016 3:00 am

### Re: Heating Curve

That energy added at those points is used to break intermolecular bonds rather than be used to increase the temperature of the substance; this is what's known as heat of fusion for changing from solid to liquid and heat of vaporization.

The slope changes between some parts of the graph because of different specific heat values. In H2O, the solid and gaseous forms have lower specific heat values compared to its liquid form; therefore, the liquid heating phase have a slope that is not as steep as the other two.