Section 12.4- Colligative Properties Flashcards
any property that depends on the number of particles and not on the identity or properties of the particles is a
colligative property
important colligative properties
- vapor pressure lowering
- freezing point depression
- boiling point elevation
- osmotic pressure
vapor pressure is a
dynamic equilibrium (rate of condensation and rate of evaporation are equal)
at equilibrium the number of molecules evaporating and the number of molecules condensing are
EQUAL
the pressure exerted by the vapor when a liquid phase and vapor phase are in equilibrium is the
vapor pressure
may be considered a measure of the escaping tendency of molecules in the liquid
vapor pressure
the higher the vapor pressure, the easier it is for
a liquid to escape and become a gas
the lower the vapor pressure, the harder it is for
liquid to escape and become a gas
a gas is highly influenced by
temperature and pressure
the higher the temperature, the higher the
vapor pressure
the addition of a nonvolatile solute to a solvent _________________ the tendency of the solvent molecules to escape from the surface of the liquid
reduces
a nonvolatile solute _______________ the vapor pressure of the solvent
lowers
using a nonvolatile solute lowers the vapor pressure requires a
higher temperature to boil
the vapor pressure lowering has an effect on
both the boiling and freezing points of the solution
the lowering of vapor pressure in solutions is a
colligative property
the temperature at which the vapor pressure of the liquid equals the atmospheric pressure
boiling point of a liquid
if the atmospheric pressure is 1 atm, the temperature is the
normal boiling point
the boiling point when a nonvolatile solute is present is
boiling point elevation (delta Tb)
the temperature at which the vapor pressures of the solid and liquid are equal
freezing point
the resulting phenomenon when the vapor pressure is lowered due to the presence of a solute and in turn lowers the freezing point of the solvent
freezing point depression (delta Tf)
boiling point elevation and freezing point depression are
colligative properties
constant values are associated with each solvent and known as the
molal boiling point elevation constant (Kb)
molal freezing point depression constant (Kf)
equation for the constants of freezing and boiling
delta Tb= mKb
delta Tf= mKf
to find the actual boiling point or freezing point of a given solution, the freezing point depression must be ________________ the normal freezing point, and the boiling point elevation must be _____________________ the normal boiling point
*subtracted from (normal freezing point - freezing point depression)
*added to (boiling point elevation + normal boiling point)
substances that do not ionize or dissociate in aqueous solutions to produce ions that can conduct an electrical current are
nonelectrolytes
compounds that dissolve in water to produce ions that can conduct electrical current are
electrolytes
dissociate or ionize essentially completely in water to give solutions that are good conductors
strong electrolytes
are generally polar covalent substances that do not dissociate completely in water and whose solutions are poor conductors of electricity
weak electrolytes
various substances that permit the passage of some molecules but not others are said to be
semipermeable membranes
the more __________- present, the more effective electroconductibity
ions
occur since the solvent is more concentrated on the side of the membrane containing pure water and more collisions per unit time by solvent molecules occur there, resulting in a net flow of water into the solution
osmosis
the pressure exerted on the membrane due to the hydrostatic pressure on the solution forcing solvent from the solution into the pure solvent at the same rate that is flows in the reverse direction
osmotic pressure
the direction of the solvent flow is always from the more ______________ solution to the more _____________ concentrated solution
more dilute to more concentrated
used to desalinate water
reverse osmosis
