A question for a lab report states this: In this experiment we used a specific heat for the solution that was equal to that of water. How would you expect a salt solution to alter the specific heat of water and why? Think in terms of how the polarity of water influences the nature of water. PLEASE HELP!
As the salt concentration increases in water the specific heat decreases (see graph on first link). For pure water, the specific heat is 1.00 cal/g-C, while for a saturated NaCl solution (brine) the specific heat is 0.786 cal/g-C.
As the amount of NaCl is increased in the solution, the hydrogen bonding structure of water is disturbed. There would be less hydrogen bonding in the salt solution than in pure water. Also, much of the water will be involved with hydrating the ions, insulating them from the rest of the solution by forming a solvent sheath around them. This apparently disrupts the ability of the water to hold heat resulting in a lower heat capacity for the salt solution.
Hope this helps.
March 18th, 2010 at 3:12 am
As the salt concentration increases in water the specific heat decreases (see graph on first link). For pure water, the specific heat is 1.00 cal/g-C, while for a saturated NaCl solution (brine) the specific heat is 0.786 cal/g-C.
As the amount of NaCl is increased in the solution, the hydrogen bonding structure of water is disturbed. There would be less hydrogen bonding in the salt solution than in pure water. Also, much of the water will be involved with hydrating the ions, insulating them from the rest of the solution by forming a solvent sheath around them. This apparently disrupts the ability of the water to hold heat resulting in a lower heat capacity for the salt solution.
Hope this helps.
References :
http://www.engineeringtoolbox.com/sodium-chloride-water-d_1187.html