2. Enthalpies of Solution Flashcards
What 2 things happen when a solid ionic lattice dissolves in water?
- bonds between the ions break to give gaseous ions (endothermic)
- bonds between gaseous ions and water made (exothermic)
What is the enthalpy change of solution?
the overall effect on the enthalpy of
- bonds between ions breaking to give gaseous ions (endothermic)
- bonds between gaseous ions and water made (exothermic)
definition
the enthalpy change of hydration
(3 things)
the enthalpy change when
1 mole of gaseous ions
dissolves in water
definition
the enthalpy change of solution
(3 things)
the enthalpy change when
1 mole of solute
dissolves in water
why do soluble substances tend to have exothermic enthalpies of solution
(4 things)
substances generally only dissolve if
energy released
is roughly the same or greater than
the energy taken in
what two things affect the enthalpy of hydration
- ionic charge
2. ionic radius
why do ions with a greater charge have a greater enthalpy of hydration?
(4 things)
- ions with higher charge better at attracting water molecules
- electrostatic attraction between ion and the water molecule stronger
- more energy is released when bonds are made
- giving them a more exothermic enthalpy of hydration
why do smaller ions have a greater enthalpy of hydration?
3 things
have a higher charge density than bigger ions
attract water molecules better
have a more exothermic enthalpy of hydration
how does ionic charge affect enthalpy of hydration?
greater charge = greater enthalpy of hydration
how does ionic radius affect enthalpy of hydration
smaller ions = greater enthalpy of hydration
what is the symbol for
the enthalpy change of hydration
△hydHθ
what is the symbol for
the enthalpy change of solution
△solHθ
