One effective and creative use of the energy in calcium chloride is in self heating containers. Water and anhydrous calcium chloride can be incorporated in an advanced container and then brought into contact with each other by pressing a button, which causes the seal between the two materials to rupture. The heat evolved in the dissolution of the calcium chloride can then be used to heat a beverage such as coffee or tea.
When calcium chloride is dissolved in water, heat is evolved since calcium chloride has a negative heat of solution. The amount of energy available depends on the concentration of crystal water; a completely water free (anhydrous) calcium chloride contains the most energy. The table below gives the theoretical maximum energy that is available from one gram of product with varying concentrations of calcium chloride.
|
|
|
|
|
|
87
|
6.9
|
93.1
|
-428
|
|
88
|
14.1
|
85.9
|
-452
|
|
89
|
21.3
|
78.7
|
-476
|
|
90
|
28.4
|
71.6
|
-499
|
|
91
|
35.6
|
64.4
|
-523
|
|
92
|
42.7
|
57.3
|
-547
|
|
93
|
49.9
|
50.1
|
-571
|
|
94
|
57.1
|
42.9
|
-594
|
|
95
|
64.2
|
35.8
|
-618
|
|
96
|
71.4
|
28.6
|
-642
|
|
97
|
78.5
|
21.5
|
-666
|
|
98
|
85.7
|
14.3
|
-689
|
|
99
|
92.8
|
7.2
|
-713
|
|
100
|
100
|
0
|
-737
|
The reason for the rapid drop in available energy as the concentration of calcium chloride decreases can be found in the heat of solution for pure anhydrous CaCl2 and the monohydrate as shown below.
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