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Alice Yang 2nd Semester Coggle (Solutions (PPM = Parts of solute in every…
Alice Yang
2nd Semester Coggle
Gas
STP (Standard Temperature Pressure)
P = 1 atm; 760 mmHg/torr
T = 273K
The molar volume of an ideal gas is 22.42 liters at STP
Boyle's Law: P1V1=P2V2
Charles' Law: V1/T1 = V2/T2
Gay Lussac's Law: P1/T1 = P2/T2
Combined Gas Law: (P1V1)/T1 = (P2V2)/T2
Avogadro's Law: V1n1 = V2n2 (n-number of moles)
Ideal Gas Law
PV=nRT
P - pressure; V - volume; n - number of moles; R - gas constant number; T - temperature(K)
Behaves in
high temperature & low pressure
D = (MP)/(RT); M = molar mass
At STP: D = (Molar Mass)/22.4L
Kinetic Energy = 1/2mv^2
(KE)avg = 3/2RT
Diffusion: Describes the mixing of gas; the rate of diffusion means the rate of mixing
Distance traveled by gas 1/Distance traveled by gas 1 = sqrt(M2)/sqrt(M1)
Effusion: Describes the passage of gas into an evacuated chamber
Rate of effusion for gas 1/Rate of effusion for gas 2 = sqrt(M2)/sqrt(M1)
Root Mean Square Velocity
Urms = sqrt(3RT/M)
R - gas constant (energy one - 8.314)
T - temperature(K)
M - molar mass in
KILOGRAM (KG)
IMF
London Dispersion Force
: the force within all the compounds
Greater molar mass = more electrons =
increased polarizability
= greater forces = greater mp/bp
Dipole-dipole Force
: the force within
polar
bonds
Hydrogen-Bond Force
: the force within OH, NH, HF bonds
Covalent bond > hydrogen > dipole-dipole > dispersion
Ion-dipole: attractions present between ionic compounds and polar molecules (in ionic aq solution)
Increase in T = increase in vapor pressure
Volatile liquids have high vapor pressure, but low bp, therefore low IMF
The strength of attraction between particles determine its state
The stronger the attraction, the higher bp for liquid and mp for solid
Intermolecular attraction - + to -
Larger charge = stronger attraction
Longer distance = weaker attraction
However, the intermolecular forces are relatively small compare to bonding forces
Solutions
PPM = Parts of solute in every 1 million parts solution
1L = 1Kg
mg of solute / kg of solution = mg of solute / L of solution
If a solution is 36 ppm by volume, then there are 36mL of solute in 1 million mL of solution
PPB = Parts of solute in every 1 billion parts solution
Energetic of Solutions Formations
- 3 steps
Separate the solute into particles (endothermic)
break up - required energy
Separate the solvent in order to leave space for solutes (endothermic)
break up - required energy
Mix separated solute and solvent together (exothermic) form
ΔHsoln = ΔHsolute + ΔHsolvent + ΔHmix
If the sum of
(ΔHsolute + ΔHsolvent) < ΔHmix
, then the ΔH solution will be exothermic
If the sum of
(ΔHsolute + ΔHsolvent) > ΔHmix
, then the ΔH solution will be endothermic
High ΔHhydration is
largest charge & smallest size
but must be
IONS
Solute
Salt
in salt water;
Sugar
in sweet drinks
Solvent
Water
in salt water;
Water
in soda
Solution
Saltwater; soda
Molarity M= moles of solute / L in solution
Molality m= moles of solute / kg in solvent
Molality varies with masses, not temperature
In order to let the solution forms (mix solute and solvent), MUST:
Solute-solvent interaction
>
solute-solvent mixing
Solute-solvent interaction
=
solute-solvent mixing
IF
Solute-solvent interaction
<
solute-solvent mixing, the solution may or may not be formed depends on the energy difference is small enough to be overcome by the increase in ΔS
LIKE Dissolves LIKE
polar in polar
non-polar in non-polar
Solubility
Solids increase with temperature increase
Larger surface area, the rate of solubility increases
Gases decrease with temperature increase
Gases increase with pressure above the solution
The larger the partial pressure, the more soluble the gas in the liquid
Solubility Limit
Saturated
When add more solute in solution, it won't dissolve
Unsaturated
Molarity < Solubility
When add more solute in solution, it will dissolve
Supersaturated
Molarity > solubility
Raoult's Law
Psolution =
Xsolvent
* Ppure solvent
Vapor Pressure Lowering
- the difference between the vapor pressure of the pure solvent and the vapor pressure of the solvent in solution
ΔP = Ppure solvent - Psolution =
Xsolute
* Ppure solvent
Modified Raoult's Law
Ptotal = Pa + Pb = Xa
Ppure a + Xb
Ppure b
Ideal Solution - not solutions are ideal, though some are close
Negative deviation
Solute and solvent are similar, with
strong
forces of attraction
ΔHsolution is large and negative
Positive deviation
Solute and solvent are dissimilar, with
weak
forces of attraction
In ideal solution, the
formed solute-solvent interactions
are
EQUAL
to the
sum of broken solute-solute and solvent-solvent interactions
If the solute-solvent interactions are stronger or weaker than the broken interactions, the solution then is nonideal
When the
solute-solvent interactions are stronger than the solute-solute + solvent-solvent
, the total vapor pressure of the solution will be
less than
Raoult's law predicted, because the vapor pressures of the solute and solvent are lower than ideal
When the solute-solvent interactions are weaker than the solute-solute + solvent-solvent, the total vapor pressure of the solution will be greater than Raoult's law predicted, because the vapor pressures of the solute and solvent are greater than ideal
Acid-Base
Buffer - restrict pH
Acid
Produce H+/H3O+
pH < 7
Base
Produce OH-
pH > 7
pH = -log[M]
pH +pOH = 14
[M] = 10^-pH or 10^-pOH
Bronsted-Lowry Model
Acids are proton donors/Base are proton acceptors H+
Conjugate pair
Ex: (H2O -> OH-) (NH3 -> NH4+)
Ka=([H][A])/[HA]
-> only weak acid and base
Electrochem
Cell Potential
Ecell = Eoxidization + Ereduction
Voltaic cell: from anode to cathode
ΔG = -nFE (spontaneous)
Cell Line
Anode||Cathode
Electrochemical Cells
from cathode to anode
Oxidation
- Reducing agent - Anode
The oxidation number of an element increases
an element loses electrons (+)
a half-reaction has electrons as products
Reduction
- Oxidizing agent - Cathode
The oxidation number of an element decreases
an element gain electrons (-)
a hale-reaction has electrons as reactants
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