Solutions Flashcards
solutions
a homogenous mixture of 2 or more substances
when do solutions form
they form when there is sufficient attraction between the solute and the solvent
solute-solvent interactions > solute-solute interaction and solvent-solvent interactions
water as a solvent
a polar molecule due to polar O-H bonds and bent shape
what does the expression “like dissolves like” mean
a solution will form if a polar solute is mixed in a polar solvent or a non polar solute is mixed in a non polar solvent
a solution will not form with a polar solute is mixed in a nonpolar solvent or vice versa
why is methanol soluble in water
it has a polar OH group to form hydrogen bonds with water
why are compounds such as iodine, oil, or grease insoluble in water
there are no attractions between the particles of a nonpolar solute and the polar solvent
the process of solubilization
- the intermolecular forces between solute molecules must be overcome.
- the intermolecular forces between solvent molecules must be overcome
- for the solvation process to take place, the energetic costs for the first two steps must be surpassed
electrolytes
dissolve in water; the process of dissociation separated them into ions forming solutions that conduct electricity
nonelectrolytes
do not separate into ions when dissolved in water. dissolve as molecules in water.
C12H22O11 (sucrose) –> C12H22O11 (solution of sucrose)
strong electrolyte
dissociate 100% in water producing positive and negative ions; can conduct an electric current strong enough to light a bulb
weak electrolyte
dissociates only slightly in water. form a solution with a few ions and mostly undissociated molecules [equilibrium]
degree of dissociation (α)
ration between the number of moles dissociated and the total number of moles of the compound
degree of dissociation for strong electrolytes
alpha = 1
degree of dissociation for nonelectrolytes
alpha= 0
gout
attacks of gout may occur when the concentration of uric acid in blood plasma exceeds its solubility of 7mg/100ml of plasma at 37 C
solubility
the maximum amount of solute that dissolves in a specific amount of solvent
what does solubility depend on
temperature
unsaturated solution
contain less than the maximum amount of solute
saturated solution
contain the maximum amount of solute that can dissolve; it has undissolved solute at the bottom of the container
categorise solute-solute interaction and solvent-solvent interactions
these interactions are of the weak type: dipole-dipole interactions, van der Waals contact
how are ionic compounds that are insoluble in water stabilised?
by strong solute-solute interactions
effect of temperature on solubility of gases
as temperature increases solubility of gases decreases
effect of temperature on solubility of solids
solubility of most solids increases as temperature increases
what happens when a saturated solution is carefully cooled?
it becomes a supersaturated solution because it contains more solute than the solubility allows
henry’s law
the solubility of a gas in a liquid is directly related to the pressure of that gas above the liquid.