OCEANS Flashcards
What determines the solubility of a solute in solvents?
The strength of interactions between solute and solvent molecules with respect to intermolecular forces.
Stronger interactions lead to greater solubility.
What type of solute is soluble in polar solvents?
Polar molecules
Polar molecules exhibit dipole-dipole interactions.
What type of solute is soluble in nonpolar solvents?
Nonpolar molecules
Nonpolar molecules exhibit id-id forces.
Do polar and nonpolar molecules mix?
Generally, they do not mix
This is due to the differing intermolecular forces.
What is the solubility behavior of ionic compounds in polar solvents?
Ionic compounds are more soluble in polar solvents like water
Ions can form strong favorable interactions with polar solvents as ions are charged.
What does lattice enthalpy measure?
The strength of ionic bonding in a giant ionic lattice
It is specific to ionic substances.
Define lattice dissociation enthalpy.
The enthalpy change when one mole of a solid ionic compound is completely dissociated into its gaseous constituent ions under standard conditions.
What type of process is lattice dissociation enthalpy?
Endothermic process
This indicates that energy is absorbed during the formation of a solid ionic compound from its gaseous ions.
How is lattice formation enthalpy defined?
The enthalpy change when one mole of a solid ionic compound is formed from its gaseous constituent ions under standard conditions.
What type of process is lattice formation enthalpy?
Exothermic process
This indicates that energy is released when the lattice structure is formed.
Can lattice enthalpy be measured directly?
No, it is calculated using experimental values for other enthalpy changes.
This calculation often involves the Born-Haber cycle.
What are the two types of enthalpies discussed that can measure lattice enthalpies indirectly?
Enthalpies of Solution (AsolH) and Hydration (AhydH)
These enthalpies provide alternative methods to assess lattice enthalpies by using principles similar to Hess’s Law.
What is the enthalpy of solution?
The enthalpy change when one mole of ionic solid is dissolved in water to infinite dilution so that the ions no longer interact under standard conditions.
What is the enthalpy of hydration?
The enthalpy change when one mole of gaseous ions is dissolved in water to form one mole of aqueous ions under standard conditions.
Is the enthalpy of hydration typically positive or negative?
Negative
This is because water molecules have + regions that naturally attract negative ions.
What is a hydrated ion?
A solvated ion surrounded by solvent molecules that are aligned in a spherical shell.
How are the enthalpy of solution and the enthalpy of hydration related?
They are combined in an energy cycle.
This relationship is essential for calculating changes in enthalpy during dissolution processes.
What is the enthalpy of hydration?
A measure of the attraction between ions and water molecules in solution
Positive ions are attracted to the o- oxygen atoms, and negative ions are attracted to the o+ hydrogen atoms.
How does the size and charge of ions affect hydration enthalpy?
Attractions are stronger with smaller ions and ions of greater charge
This explains why hydration enthalpies decrease as you move down a group and why Na+ ions have a lower enthalpy of hydration than Mg2+ ions.
What happens to lattice dissociation enthalpy with decreasing ionic radius and increasing charge?
It increases in magnitude
Stronger attractions require greater energy for dissociation.
What does entropy (ΔS) measure?
Disorder and the dispersal of energy in a system
Greater disorder equates to greater entropy.
What is the relationship between temperature and entropy?
Entropy increases as temperature increases
Particles gain energy and move faster and further apart, becoming less ordered.
Which state of matter has the greatest entropy?
Gases
What happens to entropy when a substance melts or evaporates?
There is a sudden increase in entropy
This increase occurs because the transition from solid to liquid (fusion) or liquid to gas (vaporization) results in greater disorder.