Name:
Date:
Heating Curve of Water Activity
Water molecules have a strong attraction to one another. Because of this property,
water has high melting and boiling points and a high specific heat. In this activity, you
will plot the heating curve of water and explain what each part of the curve represents
at the molecular level.
Procedure
Use the data in the table to plot a heating curve of temperature versus time for a 180-g
sample of water as it is heated at a constant rate from -20°C to 120°C. Draw a best-fit
line through the points. Note the time required for water to pass through each segment
of the graph.
Time and Temperature Data for Water
Time Temperature Time Temperature
(min)
(°C)
(min)
(°C)
0
1
2
3
4
5
6
7
8
9
10
11
12
-20
0
0
9
26
42
58
71
83
92
98
100
100
13
14
15
16
17
18
19
20
21
22
23
24
25
100
100
100
100
100
100
100
100
100
100
100
100
120
Think Critically
1. What experimental factors would affect the lengths of the flat regions of the graph?
2. What experimental factors would affect the slope of the curve between the flat
regions?
Name:
Date:
3.
Analyze each of the five regions of the graph (label them A-E), which are
distinguished by an abrupt change in slope. For each segment, indicate what is
physically happening to the molecules (for example, boiling), whether it is a change
that makes the molecules move faster or farther apart, and if the change in energy
is kinetic or potential.
A.
B.
C.
D.
E.
4.
What would the heating curve of ethanol look like? Ethanol melts at -114°C and
boils at 78ºC. Sketch ethanol’s curve from -120°C to 90°C.