Posted by Mary on .
Can someone help me please?
1)Calcium chloride is found in salt mixtures that are used to melt ice on the roads in winter. The dissolving of CaCl2 is exothermic. Provide two reasons why CaCl2 is a good choice for this application as compared to a salt such as NaCl or a salt that dissolves endothermically.
Several things for you to consider.
NaCl rusts the exterior of the metal used in sutomobiles and other forms of transporation. I'm not sure CaCl2 is much better along these lines but it has other advantages.
CaCl2 is exothermic, meaning that heat is given off when it dissolves. Therefore, CaCl2 is better than another salt, such as NaCl, that does not evolve heat upon soluton because CaCl2 provides heat from the dissolution of the material as well as the ions it furnishes to melt the snow and ice.
NaCl, and other salts like it, consist of two ions when they dissolve; that is, Na ion and Cl ion. But CaCl2 consists of three ions. There is one Ca ion and two Cl ions. Therefore, CaCl2 has more of a "melting power" than 1:1 salts such as NaCl because it consists of more ions for the same number of mols of salt used.
A salt that dissolves endothermically, meaning that it absorbs heat when it dissolves, obviously is less effective because sopme of the energy that could be going to melt the snow and ice is going to dissolve the salt.
I hope this gets you started on an answer.
Yeah, I thought that because CaCl2 has more particles, it would be better, but I thought my teacher said NaCl has more particles, which doens't make sense.