CaCl2 lattice energy is -2247 kj/mol delta H of solution is -46 kj/mol
CaI2 lattice energy is -2059 kj/mol delta H of solution is -104 kj/mol
The enthalpy of energy should just be in kJ.
which ion Cl ‾ or I ‾, is more strongly attracted to water?
Please explain how you figured it out because I’m lost. Thank you
basically add up the two numbers
hydration is 2247 + 46
as hydration is able in this case to overcome the lattice energy AND then release some energy to spare.
Cl- is more attrracted as the total number above is greater
34. (a) Use the following data to calculate the enthalpy of hydration for calcium chloride and calcium
iodide. Lattice Energy ∆Hsoln
CaCl2(s) –2247 kJ/mol –46 kJ/mol
CaI2(s) –2059 kJ/mol –104 kJ/mol
Using the equations for lattice enthalpy and the enthalpy of solution for each ionic solid, we can calculate the
enthalpy of hydration of each compound.
CaCl2(s) → Ca2+(g) + 2Cl–(g) ∆H = –LE = –(–2247) kJ/mol = 2247 kJ/mol
Ca2+(g) + 2Cl–(g) → Ca2+(aq) + 2Cl–(aq) ∆Hhyd = ? kJ/mol
CaCl2(s) → Ca2+(aq) + 2Cl–(aq) ∆Hsoln = –46 kJ/mol
∆Hhyd (CaCl2) = –2293 kJ/mol
CaI2(s) → Ca2+(g)I–(g) ∆H = –LE = –(–2059) kJ/mol = 2059 kJ/mol
Ca2+(g) + 2I–(g) → Ca2+(aq) + 2I–(aq) ∆Hhyd = ? kJ/mol
CaI2(s) → Ca2+(aq) + 2I–(aq) ∆Hsoln = –104 kJ/mol
∆Hhyd (CaI2) = –2163 kJ/mol
(b) Based on your answers to part a, which ion, Cl– or I–, is more strongly attracted to water?
The enthalpy of hydration of calcium chloride is more exothermic than that of calcium iodide. Since these
compounds contain a common cation Ca2+, this difference arises from the halide ion. Since more exothermic
energy is associated with the hydration of the chloride ion, it is more strongly attracted to water.Source(s): http://personal.stevens.edu/~mtoledo/Ch11-HW.pdf