# Use the following data to calculate the enthalpy of hydration for calcium chloride and calcium iodide.?

Lattice energy of CaCl2 is -2247 kj/mol delta H of solution is -46 kj/mol

hydration is 2247 + 46
because the hydration is able, in this case, to overcome the energy of the network And thus to release a little energy to resell.

Cl- is more attracted because the total number above is higher

Source(s): Soc

Hydration enthalpy table

34. (a) Use the following data to calculate the enthalpy of hydration of calcium chloride and calcium
iodide. Grid 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 solution enthalpy 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
∆Hid (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
∆Hid (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. Once these
contain a common cation Ca2+, this difference comes from the halide ion. Because it’s more exothermic
the energy is associated with the hydration of the chloride ion, it is more strongly attracted to water.