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.
thanks
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.
It's great that you're thinking critically about this! The number of particles in a salt does not depend on the type of ion it is made of, but rather on the ratio of ions in the formula. In the case of NaCl and CaCl2, NaCl consists of one sodium ion (Na+) and one chloride ion (Cl-), whereas CaCl2 consists of one calcium ion (Ca2+) and two chloride ions (Cl-).
So, when both salts dissolve in water, NaCl will dissociate into two ions (Na+ and Cl-) while CaCl2 will dissociate into three ions (Ca2+ and 2 Cl-). Therefore, CaCl2 has more particles for the same number of moles of the salt used, making it more effective for melting snow and ice.
Remember, it's the number of particles, not the type of ions, that determines the "melting power" of a salt.