Dissolving 6.49 g of CaCl2 in enough water to make 306 mL of solution causes the
ID: 752833 • Letter: D
Question
Dissolving 6.49 g of CaCl2 in enough water to make 306 mL of solution causes the temperature of the solution to increase by 3.44 oC. Assume the specific heat of the solution and density of the solution are the same as water?s (about 4.18 J/goC and 1.00 g/cm3, respectively) Calculate ?H per mole of CaCl2 (in kJ) for the reaction under the above conditions. Hint given in feedback Aside, the ?H per mole for dilution depends on the process. For example, more energy is released when starting with a large volume of water (infinite dilution), than when starting with a small volume of water. Why do you think this happens?Explanation / Answer
moles of CaCl2 = 6.49/110.98 = 0.05848 moles mass of solution = 306 x 1 g/cc = 306 gms Heat released = 4.18 x 3.44 x 306 = 4400.0352 J delta H per mole of CaCl2 = Heat released/ moles = 75.24 KJ/mole