Enthalpy, CaCl2 solutions

The two chlorides have almost identical solubilities, except that the NaCl solution has a molar concentration of ions of 2 x 5.4 = 10.8 mol dm and that of the CaCl2 solution is 3 x 5.0 = 15.0 mol dm . Sodium carbonate solution (molar ion concentration = 6.03 mol dm ) is less concentrated than that of sodium chloride (molar ion concentration = 10.8 mol dm ). When both cations and anions are doubly charged, as in CaC03, the relatively high lattice enthalpy predominates to make the compound insoluble. Calcium sulfate is only sparingly soluble, but sodium sulfate is soluble. The double charge on the calcium ion favours a larger lattice enthalpy compared to the enthalpy of hydration. 

A U. luO-L solution is made by dissolving u.44i gof CaCl2(s) in water, (a) Calculate the osmotic pressure of this solution at 27 "C, assuming that it is completely dissociated into its component ions, (b) The measured osmotic pressure of this solution is 2.56 atm at 27 C. Explain why it is less than the value calculated in (a), and calculate the van t Hoff factor, i, for the solute in this solution. (See the A Closer Look box on Colligative Properties of Electrolyte Solutions in Section 13.5.) (c) The enthalpy of solution for CaCl2 is AH = —81.3 kj/mol. If the final temperature of the solution is 27 °C, what was its initial temperature (Assume that the density of the solution is 1.00 g/mL, that its specific heat is 4.18 J/g-K, and that the solution loses no heat to its surroundings.)... 

Calculate the enthalpy of formation in aqueous solution of 1 mol of NaCl, CaCl2, and ZnBta, assuming complete dissociation. 

When 23.6 g of calcium chloride, CaCl2, was dissolved in water in a calorimeter, the temperature rose from 25.0°C to 38.7°C. If the heat capacity of the solution and the calorimeter is 1258 J/°C, what is the enthalpy change when 1 mol of calcium chloride dissolves in water The solution process is... 

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