Name ______________________________________ Date ___________________ Period _____________
Heating and Cooling Curves
Heating Curves
A heating curve shows how the _____________
(y-axis) changes as a substance is heated up at a
constant rate over _____________ (x-axis).
Heating
Point A - substance exists at a _____________
state. As time passes, _____________ is added
to the substance. This causes the molecules of the
substance to _____________ more rapidly which
we detect by an increase in _____________ in the
substance.
Point B - the temperature of the substance is
_______°C which is the “_____________ point”
(Tm) of water. The solid begins to _____________ . Both _____________ and _____________ are present.
● The energy put in the substance between minutes 5-9 (between B&C) was used to convert the substance from a
____________ to a ____________ . This heat energy is called the “latent heat of fusion.”
Point C - the substance is completely ____________ and in the ____________ state.
● Between 9 & 13 minutes (between C&D) the added energy increases the ____________ of the substance.
Point D - the temperature of the substance is _______°C which is the “_____________ point” (Tb) of water. The liquid
begins to _____________ .Both _____________ and _____________ are present.
● Between 13 and 18 minutes (between D&E) the energy added to convert the _____________ to the
_____________ state is called the “latent heat of vaporization.”
Point E - the substance is completely ____________ and in the ____________ state.
● Beyond point E the substance is still in the _____________ phase but molecules are moving _____________ as
indicated by the increasing temperature.
What element is this heat diagram diagram for? Compare Tm and Tb of the heating curve above with the values below.
This is the heating curve of the element
________________ which has a melting
point of ____________ and boiling point of
____________.
Cooling Curve
A cooling curve shows how the temperature (y-axis) changes as a substance is cooled down a constant rate over time
(x-axis). Kinetic energy is (lost / gained) during a cooling curve therefore the temperature goes (up / down).
● The substance starts in the ________________ phase.
● At the first plateau where temperature is (changing / constant), the substance changes from a
________________ to a ________________. The temperature at this region is also called the
________________ point (Tc) and is the same temperature as Tb in the substance’s heating curve.
●
●
When temperature continues to decrease after Tc, the substance is completely in the ________________ state
and continues to (lose / gain) ________________ .
At the second plateau the ________________ begins to ________________ - the temperature in this region is
called the ________________ point (Tf). Both ________________ and ________________ states exist.
●
When the temperature continues to drop after the plateau, the substance is completely in the
________________ state.
Cooling Curve Practice
Given the data table below, draw a cooling curve for water. Draw the heating curve of water given the following data
and label the graph with when it’s SOLID, LIQUID, and GAS and label the condensation (Tc) and freezing points (Tf).
Temperature
(C)
0
140
5
120
10
100
15
100
20
80
25
60
30
40
14
0
12
0
Temperatur
Time (min)
10
0
80
60
40
20
0
40
5 10 15 20 25 30
45 50 55
35