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ria b period 3 semester 2 :pencil2: it's time to final this up!! :D…
ria b period 3 semester 2 :pencil2: it's time to final this up!! :D
empirical formulas :heavy_multiplication_x:
the formula of a compound expressed as the smallest whole-number ratio of subscripts of the elements in the formula
percent to mass, mass to mole, divide by small, multiply until whole
combustion analysis
elements almost always include C and H
We must know the mass of the unknown substance
unknown is burnt in oxygen
CO2 and water are the products. Nitrogen sometimes shows up
all carbon becomes carbon dioxide, and all H becomes water
oxygen by subtraction
gas laws :explode:
gases are weird things
they expand to fill their container, they flow, they aren't very dense, they can be compressed, and they EFFUSE and DIFFUSE
EFFUSION: escaping DIFFUSION: spreading
pressure: the collision of molecules within the walls of a container
LAWS and density which isn't a law but i wanted all formulas to be here
boyles law
: p1v1 = p2v2
charles' law
: v1/t1 = v2/t2
gay lussac's law
: p1/t1 = p2/t2
ideal gas law
: PV = nRT
combined gas law
: p1v1/t1 = p2v2/t2
avogadro's law
: n1/v1 = n2/v2 at low pressures
dalton's law of partial pressures
Ptotal = P1 + P2
density
= MP/RT or molar mass/volume
IMPORTANT: 1 atm = 760 mmHg = 760 torr = 101.325kPa
gases can be
ideal
, but these gases actually do not exist
HIGH TEMP AND LOW PRESSURE WITH SMALL, NONPOLAR PARTICLES= the closest one can be to an ideal gas
KMT
gases are tiny particles, they have elastic collisions, high kinetic energy, no forces of attraction, avg kinetic energy depends on temperature
thermochemistry :fire:
the si unit for measuring heat is the joule. it equals one newton x meter or 1kg x m^2/s^2
energy is the capacity to do work. thermochemistry divides energy into the system and its surroundings
there are many types, but the important ones are kinetic, potential, and thermal energy
enthalapy is heat released or absorbed during a process or :small_red_triangle:H
absorbed: endothermic released: exothermic
specific heat is the amount of heat required to raise the temperature of one gram of a substance by one degree
q = mc :small_red_triangle:T
STUFF TO MEMORIZE
heat of fusion: 6.01 kJ/mol or 333 J/g
heat of vaporization: 40.7 kJ/mol or 2240 J/g
Cice is 2.09 J/g C
Csteam is 1.87 J/g C
calorimetry exists and it is mcat = -mcat. also phase changes exist and you use the heat of fusion and vaporization to determine the amount of energy needed to undergo a phase change, since you can't use mcat is there's no change in temperature. ((these are the confusing ones))
solutions :sweat_drops:
all solutions are homogenous
solute --> dissolved substance
solvent --> dissolving medium
saturated solution: max amount of solute is dissolved
unsaturated solution: max amount of solute hasn't been reached
WAYS TO MEASURE CONCENTRATION
grams per liter (g/L)
molarity: moles of solute/volume of solution
parts per million: mass of solute/mass of solution * 1,000,000
percent composition: mass of solute/mass of solution * 100
kinetics :zap:
reaction rates: how fast does a reaction go
molecules must collide to react
must have
sufficient energy
must be in a
correct orientation
nyoom goes the reaction
measured in concentration/time
differential rate law
must use data to derive it
if it is single step, use coefficients
rate expressions (no data needed)
factors affecting rate
increasing surface area
increasing concentration
increasing temperature
presence of catalysts
equilibrium :scales:
le chatelier's principle: systems at equilibrium experiencing stress undergo changes to relieve stress
pressure increase --> shifts to the side with fewer moles of gas
reversible reactions: products react to re-form reactants
equilibrium is when the forward and backwards rates equal the same in a reversible reaction
law of mass action: k = products/reactants. coefficents are the exponents
no solids or liquids. they do not affect concentration.
can also use partial pressures in the equation
product favored equilibrium: k>1
reactant favored equilibrium: k<1
reaction quotient
q<k reaction shifts to the right. products.
q = k system is at equilibrium
q>k reaction shifts to the left. reactant favored
ICE tables
step 2: ice the problem
step 3: solve for x in law of mass action
step 1: write law of mass action
k
Acids and Bases :biohazard_sign:
bases: bitter and soapy, and are solids
acids: sour and electrolytes. they react with metals and produce h2. aqueous
two definitions:
arrhenius model:acids produce hydrogen ions, bases produce hydroxide ions (only strong bases)
bronsted lowry: acid are proton donors, bases are proton acceptors
strong acids and bases neutralize each other and produce a salt and water
strong acids dissociate completely in solution
strong bases do the same
ok ria but what about weak acids and bases
im glad you asked, remember that equilibrium stuff? well it's coming in handy now
products/reactants = Ka or Kb
you can ice these problems too! and use the five percent rule!
definitions:
conjugate base: base that forms when an acid loses a proton
amphoteric: a species that can donate or accept a proton
conjugate acid acid that forms when a base gains a proton
ph and poh
winnie the poh
ph + poh = 14
ph measures concentration of hydrogen ions
10^-ph = [H+]
ph = -log[H+]
poh measures concentration of hydrogen ions
10^-poh = [OH-]
poh = -log[OH-]
[H+] x [OH-] = 10^-14
Salts :crystal_ball:
pretend the crystal ball is a salt crystal
salts are ionic compounds so they get separated in water
they will react with water to form either an acid or a base
if it is strong, it comes apart completely again!
when a weak acid or a base is paired with a strong one, the byproduct of H+ or OH- determines the charge of the salt
when both are weak, we need to look at the Ka and Kb. strongest wins
percent dissociation is just [H+]/[HA] x 100 where HA is the weak acid. same for bases just with OH- and a base
honestly this should be part of acids and bases but that branch is too big