22.3 factors affecting lattice enthalpy and hydration

Question 1

what are the general properties of ionic compounds?

Answer 1

high mp and bp
soluble in polar solvents
conduct electricity when molten or in aq solutions

Question 2

what do the values of lattice enthalpy depend on?

Answer 2

ionic size
ionic charge

Question 3

what is the effect of ionic size on lattice enthalpy?

Answer 3

ionic radius increases
attraction between ions decreases
lattice energy less negative
melting point decreases

Question 4

what is the effect of ionic charge on lattice enthalpy?

Answer 4

ionic charge increases
attraction between ions increases
lattice energy becomes more negative
melting point increases

Question 5

what does the magnitude of lattice enthalpy give a good indication of?

Answer 5

melting point of an ionic compound

Question 6

what effect does ionic size have on hydration enthalpy?

Answer 6

ionic radius increases
attraction between ion and water molecules decreases
hydration energy less negative

Question 7

what effect does ionic charge have on hydration enthalpy?

Answer 7

ionic charge increases
attraction with water molecules increases
hydration energy becomes more negative

Question 8

how do you dissolve an ionic compound in water?

Answer 8

attraction between the ions in the ionic lattice must be overcome

Question 9

what happens to the enthalpy change if the same of the hydration enthalpies is larger than the magnitude of the lattice enthalpy?

Answer 9

the overall enthalpy change will be exothermic and the compound should dissolve