Week 2 Day 1 Flashcards
solute
thing being dissolved
solvent
thing doing the dissolving (often water)
Solution
result of dissolving solute in solvent
M
Molarity
moles of solute / liters of solution
*uses volume of solution not solvent
density of water
1 g/ml at 4ºC, less at other temps
m
Molality
moles of solute / kg of solvent
*molality uses mass of solvent
percent by weight to volume (%w/v)
grams of solute / 100 ml of solution
Percent by weight to weight (%w/w)
grams of solute / 100 g of solution
ppm
(grams of solute/grams of solution) * 1,000,000
1 equivalent (EQ)
1 mole of “reactivity”
Ex. Na+ = one equivalent
Ca++ = two equivalents
osmolarity
Concentration of a solution expressed as total number of solute particles per liter
ex: the osmolarity of a 1 M solution of NaCl is 2 Osm
Solubility
the maximum amount of solute that will dissolve in a solvent
usually has units of mass/vol
ÂHsolute
the energy needed to break up solute
usually > 0
ÂHsolvent
the energy needed to break up solvent
usually > 0
ÂHmix
the energy we get back by the new arrangement
usually < 0
ÂHsolution
total energy change during dissolving of solute
> 0 needs energy (endothermic)
< 0 gives off energy (exothermic)
Effect of pressure on solubility
Increased pressure causes more gas to dissolve into solution
S = kH * Pgas
kH is specifec for each gas and is temperature dependent
Effect of temperature on solubility
- increased temperature increases solubility of liquids and solids
- increased temperature decreases solubility of gases
Colligative properties of solution
- vapor pressure decreases with increasing solute concentration
- boiling point increases with increasing solute concentration
- freezing point decreases with increasing solute concentration
- osmotic pressure increases with increasing solute concentration
Vapor pressure
pressure of the vapor caused by the evaporation of a liquid above the sample of liquid in a closed container.
Vapor pressure, Raoult’s law
Ps = Xs * Pºs
Ps is vapor pressure exerted by solute
Xs is the mole fraction of s in the solution
P°s is vapor pressure of pure S
Osmotic pressure
water wants to move from high concentrations to low
Π = M * R * T
Π is osmotic pressure
M is molar concentration
R is universal gas constant
T is temperature
Colloids
contain particles larger than molecules suspended in a solvent
osmole
number of moles of solute that contribute to osmotic pressure
dalton
atomic mass unit (amu)
reverse osmosis
when the solvent goes from low concentration to high concentration b/c the hydrostatic pressure is > osmotic pressure
hydrostatic pressure
the pressure of the blood moving through the artery pushes the water out to the interstitial space. The osmotic pressure brings the water back into the blood vessel.
miscible
Soluble. Able to be mixed to form a solution.
solvation
water’s negative end going toward cations and positive end going toward anions.
inherently exothermic
Vapor pressure equation
Log(P) = A + (B/T)
surfactant
hydrophilic end that interacts with the water molecules and hydrophobid tail that prevents water molecules from interacting with each other. Reduces surface tension
LaPlace’s Law sphere
ÂP = (surface tension) *(2/R)
La Place’s Law- cylinder
ÂP = (surface tension) * (1/R)
surface tension units
N/m
Calusius-Clapeyron equation
used to estimate the vapor pressure at another temp if the VP at one temp is known and the enthalpy of vaporization is known.
log (P) = A + B/T
