Chapter 8 Flashcards
Mol /kg of solvent
Molality
moles of solute/Liter of solution
Molarity
Percentt by weight
allows you to measure out a volume of medicine in a syringe, and calculate the mass of the drug
Percent by volume
not on the test
Equivalents (Eq)
Analogous to mole
Equivalent definition
one Eq of a substance contains one mole of chemical reactivity
Ex One Eq of an acid can deliver
one mole of H+ ions
1 Eq/mol of H+
Ex calcium has
2 Eq /mol
1 mol is expressed in
Eq/L
1 mol of Ca is
1 mol / 2 eq
Parts per million
can be used as away to define concentration
PPM calculates as
grams of solute per one million grams of solution
What is the concentration of a solution in parts per million,
0.02/1000
Solubility
the mass of solute that will dissolve in a given amount of solvent
NACL is
very soluble in water
O2 is
not very soluble in water
A saturation solution contains
the maximum amount of solute as defined by its solubility
Supersaturated solution
contains a concentration greater than its solubility limit. The solute precipitates out
Example of supersaturation (2)
- excessive amount of ca2 in the blood precipitate out as calcium crystals forming kidney stones
- Sodium acetate crystals precipitate out of supersaturated solution
Factors affecting solubility: Increases pressure
Increase pressure = increase gas solubility in a liquid
Factors affecting solubility: Increasing Temperature
Increase solids & Liquids solubilities in other liquids
Factors affecting solubility:Increasing temperature, ______gas solubility in a liquid
Decrease solubility in a liquid
Henry’s Law
give relationship between pressure and solubiliy
S=
S= K(h) P(gas) S= Solubility K(h) = Henry's constant
Henry’s law
if you double the pressure in the chamber with pure oxygen, the amount of oxygen dissolve in the water doubles to 84mg/L
Henry’s law
but if you have mix of gases, then you have to account for partial pressure. For examples, @ 2 atm in the chamber we have mix of 50% oxygen & 50% nitrogen
The henry’s law constant for oxygen in water 0.042g/L/atm at 25C. What is the solubilityis mg /L of O2 in pure water at 740 torr room air ?
Fist convert torr to atm = 0.974 atm oxygen is 21% : (0.21) (0.974) = 0.204 atm now plug in number S= (0.042)(0.204)= 0.0086g/L Concert to mg/L Final : 8.6mg/L
Heats of solution
forming solution can be endothermic (solution gets cold) exothermic ( solution gets hot) depending on the intermolecular forces and particle interaction between the solute particles themselves and the solvent particles.
Lattice energy
the attraction of solute particles for each other
Solvation energy
the attraction of solute particles and solvent molecules
When a solution form if lattice> solvation
endothermic (because it takes energy out of the solvent to break apart the lattice)
When a solution form if lattice < solvation
exothermic , because energy is released into the solvent