Lithium iodide has a lattice energy of −7.3×102kJ/mol and a heat of hydration of −793kJ/mol. Find the heat of solution for lithium iodide. Determine how much heat is evolved or absorbed when 10.0g of lithium iodide completely dissolves in water.

Delta H of solution = -Lattice Energy + Hydration
Delta H of solution=- (-730)+(-793)
Delta H of solution= -63kJ/mol

Now we find moles of LiI:
10gLiI/133.85g=.075moles
multiply moles to the delta H of solution to cross cancel moles. .75moles x -64kJ/mol =4.7

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Tringa0 Tringa0 · Answer 2 · 2019-09-10T08:24:51+02:00

Answer:

113.6567 kiloJoules of heat is evolved or absorbed when 10.0 g of lithium iodide completely dissolves in water.

Explanation:

Lithium iodide has a lattice energy = [tex]\Delta H_{lat}=-7.3\times 10^2 kJ/mol[/tex]

Lithium iodide has a heat of hydration = [tex]\Delta H_{hyd}=-793 kJ/mol[/tex]

Heat of the solution of lithium iodide :

[tex]\Delta H_{soln}=\Delta H_{lat}+\Delta H_{hyd}[/tex]

[tex]=-7.3\times 10^2 +(-793 kJ/mol)[/tex]

= -1,523 kJ/mol

Mass of lithium iodide = 10.0g

Moles of lithium iodide = [tex]\frac{10.0 g}{134 g/mol}=0.07462 mol[/tex]

Heat of the solution of lithium iodide when 0.07462 mol is dissolved: Q

[tex]Q=Moles\times \Delta H_{soln}=0.07462 mol\times (-1,523kJ/mol)[/tex]

Q = -113.6567 kJ

(Negative sign indicates that energy released which means that temperature of the solution after dissolving lithium iodide will increase.)