13.1.3 - Enthalpy changes of solution and hydration Flashcards
Why do most ionic compounds dissolve in water?
The ionic lattice is broken down and the ions become surrounded with water molecules so ions are hydrated
What is the enthalpy change of solution?
The enthalpy change when one mole of ionic solid dissolves in water to form an infinitely dilute solution.
What is the enthalpy change of hydration?
The enthalpy change when one mole of an ion in its gaseous state is completely hydrated in water
What is an infinitely dilute solution?
When a solution reaches a point where further dilution makes no difference.
Write an equation for the enthalpy change of solution for sodium chloride.
NaCl (s) = Na+ (aq) + Cl- (aq)
Write an equation for the enthalpy change of hydration for a sodium ion.
Na+ (g) = Na+ (aq)
Are values for the enthalpy change of solution and hydration positive or negative or both?
Enthalpy change of solution = negative or Positive
Enthalpy change of hydration = always negative
What is the name of the interaction between an ion and water when it’s being hydrated?
Ion - dipole interaction
What happens to the value of enthalpy change of hydration when charge density increases?
It becomes more negative as there is a stronger attraction to water
