Oceans Flashcards
What are the 3 factors determining relative solubility of a solute in a solvent
Temperature
Molecular size
Polarity (imbs)
What are hydrated ions
An ion surrounded by water molecules in a spherical shell
An experiment was carried out to compare the solubility of sodium chloride in two different solvents at 25 degrees C. In water, solubility in g per 100g solvent was 35.92, whereas in hexane it was 0.00. Explain these results.
sodium chloride - has strong ionic bonds
water - has strong h bonds
when dissolved, NaCl and water create strong ion dipole bonds
the energy released in ion dipole bond formation compensates for the energy needed to break the bonds in water and NaCl
whereas hexane has weaker id-id bonds with NaCl, which are do not release enough energy to compensate for H bonds breaking
Define enthalpy change of solution
the enthalpy change when one mole of ionic solid dissolves in water to form one mole of aqueous ions, in standard conditions
Define lattice (formation) enthalpy
the enthalpy change when one mole of ionic solid is formed from gaseous ions, in standard conditions
Define enthalpy change of hydration of ions
The sum of the enthalpy changes when gaseous ions become fully hydrated by water to form one mole (each) of aqueous ions, in standard conditions
How does a greater charge density affect lattice enthalpy and enthalpy of hydration
Greater charge density, better at attracting molecules
- better at attracting water, imb bonds are stronger, more energy released when formed, more exothermic hydration enthalpy
- better at attracting each other, stronger ionic bonds, more energy released in formation, more exothermic lattice enthalpy
Define entropy
The measure of disorder or
The number of ways particles can be arranged
Give the equation to calculate total entropy change
Give the equation to calculate entropy change of the system
Give the equation to calculate entropy change of surroundings
