chem chap 11&13 Flashcards
what is molarity
moles of solute/liters of solution (M)
what is mass percent
mass of solute/mass of solution x100
what is molality
moles of solute/kg of solvent (m)
what is mole fraction
moles of a/total moles (Xa)
what is normality
number of equivalents/liter of solution (N)
explain normality
when you have multiple ions for every mole of a molecule
H2SO4 has two H+ ions for every mole of H2SO4 so 2eq/L
what are the steps in solutions formation
- the solute separates into individual components (expanding solute)
- the intermolecular forces in the solvent are overcome to make room for the solute (expanding solvent)
- solute and solvent interact to form the solution
does the solute and solvent expanding require or release energy
require energy since overcoming the intermolecular forces takes energy (endothermic)
does a solution forming absorb or release energy
release (exothermic)
solutions form between similar compounds or different compounds
polar molecules form solutions with polar molecules
nonpolar molecules form solutions nonpolar molecules
why do water and oil not mix
because ΔH1 and ΔH2 are large (exo) because oil is a large molecule and water has hydrogen bonding (lots of energy required)
ΔH3 is small because the molecules only minimally interact with eachother (LDF and induced dipole)
ΔH of solutions is large so no solution forms
what factors affect solubility
polarity (structure)
pressure (henry’s law)
temperature
what is henry’s law
C=kP where:
C is the molarity
k is a constant that varies
P is the partial pressure of the gas solute above the solution
as the temperature of a gas increases the solubility
decreases (sulphates act as gases)
why is the smallest gas the least soluble
because it is harder to get it into a solution
why do nonideal solutions that react poorly have a positive deviation
because the poor reaction weakens the surface pressure (bonds are less strong) which allows for more vapor pressure = positive deviation
why do nonideal solutions that react well have a negative deviation
because the good reaction strengthens the surface pressure (strong bonds) which allows for les vapor pressure = negative deviation
nonideal solutions can have an ideal deviation, why
if they have similar structures and around the same amount of LDF they’ll act ideally
what is osmotic pressure
the pressure that is present on the solution after osmosis
what is an isotonic solution
solutions that have the same osmotic pressure
how do you reverse osmosis
if you apply an external pressure greater than the osmotic pressure
what is the vant hoff factor
moles of particles in solution/moles of solute dissolved (i)
what are the adapted equations that include i
ΔT=iKm
Po=iMRT
Psoln=(mol of solv/(i x mol of solute) +mol of solv) x Psolv
what does the equilibrium depend on
- initial concentrations
- relative energies of reactants&products
- relative degree of organization of reactants&products
K of reverse reaction
1/K
what if the reaction is doubled what happens to K
reaction x n = K^n
to combine reactions what do you do to the K
multiply the different K instead of adding them like with enthalpy
what phases affect the K and which dont
aqueous and gas states affect K
solids and liquids do not
what does a large K value signify
the equilibrium lies to the right
what does a small K value signify
the equilibrium lies to the left
what do you use Q for
to verify where the reactions lies
if Q=K
system is in equilibrium
if Q>K
too much product, will shift to the left
if Q<K
too much reactant, will shift to the right
how does the addition/removal of moles affect the equilibrium
shift away from the added
shift towards the removed
liquids and solid dont affect equilibrium
how do you change the pressure of an equilibrium
add/remove a gaseous reactant or product
change the volume of the container
how does a change in pressure affect the equilibrium
shift towards the side with the least moles if volume is decreased
shift towards the side with the most moles if volume is increased
only count aq/g moles
how does a change in temperature affect the equilibrium
the energy available will be consumed
if energy is added the reaction will shift towards the side that doesnt consume energy (will consume energy in the process)
how do you find the pressure of a gas
P=CRT where:
C is the molarity
R is 0.08206 (atm)
T is the temp. (K)
how do you convert Kp to K and vice versa
Kp = K(RT)^Δn
where Δn is the (sum of the coefficients of gaseous products) - (sum of the coefficients of the gaseous reactants)
