quiz 8 Flashcards
molarity equation
moles (of solute)/liters (of solution)
dilution equation
M1V1=M2V2
arrhenius definition of acids
chemicals that increase the concentration of H+ (protons)
ex: HCl
arrhenius definition of bases
chemicals that increase the concentration of OH-
ex: NaOH
a solution is acidic if
it has more moles of acid than base, which means its pH is less than 7
a solution is basic if
it has more moles of base than acid, which means its pH is greater than 7
a solution is neutral if
it has an equal number of moles of acid and moles of base, meaning that its pH is exactly 7
bronsted-lowry definition of acids
chemicals that donate protons, AKA proton donors
bronsted-lowry definition of bases
chemicals that accept protons, AKA proton acceptors
H+ vs H3O+
they mean the same thing
strong acids
- fully disassociate (separate) into their component ions, aka complete ionization
- are strong electrolytes
weak acids
- do not fully disassociate (separate) into their component ions
- are weak electrolytes
strong bases
full disassociate (separate) into their component ions, AKA complete ionization
weak bases
-do not fully disassociate (separate) into their component ions
true or false, water reacts with itself in an acid-base reaction
true, this is self-ionization
value of [H3O+] and [OH-] in pure water
both 10^-7 M
diprotic acids
- are acids that contain two acidic protons (ex H2SO4 has 2 H+, AKA acidic protons)
- every 1 mole of diprotic acid can react with 2 moles of OH- instead of just one
- similarly, acids with three acidic protons (ex H3PO4) can react as 1 mole of acid to 3 moles of OH-
buffer solution
- resists change in pH and keeps pH level constant
- is created by making a solution where moles of weak acid and moles of conjugate base are present in 1 to 1 ratio
conjugate base
- on the reactants side
- is the acid after donating a proton, thus becoming a base itself
conjugate acid
- on the reactants side
- is the base after accepting a proton, thus becoming an acid
how to use a burette
amount dispensed = final volume - initial volume
titrant
- what goes into the buret for titration
- concentration is always known
analyte
what is in the beaker during titration
-concentration is always unknown, to be determined from the titration experiment
phenolphthalein
- an acid-base indicator
- turns pink in basic solution
- goes into the analyte solution
once a reversible reaction reaches equilibrium, what happens to the rate of the forward reaction and rate of reverse reaction?
they become equal
once a reversible reaction reaches equilibrium, what happens to the concentration of reactants and products?
- both concentrations become stable
- but [reactants] does not always equal [products]
in a reversible reaction, when is the rate for the forward reaction the fastest and slowest?
- fastest at the very beginning
- slowest at equilibrium
when is the rate for the reverse reaction the fastest?
-at equilibrium
equilibrium can only be achieved when
- the reaction is reversible
- the reaction takes place in a closed system
- none of the chemical compounds precipitate as a solid
equilibrium constant
- Keq=[products]/[reactants]=([C]^c[D]^d)/([A]^a[B]^b) when aA + bB cC + dD (lowercase are coefficients, uppercase are reactants/products)
- only take the concentrations of aq solutions and gases, and exclude solids and liquids
at what Keq does the reaction become irreversible?
- at Keq>10^10
- this means that it’s 0% reactant, 100% product
at what Keq does the reaction become NO reaction?
at Keq<10^-10
-this means that it’s 100% reactant, 0% product
le chatelier’s principle
when a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance
ways to disturb an equilibrium
- change the concentration of one of the chemicals involved
- change the temperature
- change the volume of the system
what change in concentration would make a system shift to the left?
- adding product
- removing reactant
what change in concentration would make a system shift to the right?
- adding reactant
- removing product
what change in temperature would shift a system to the left?
- adding energy to an exothermic reaction
- removing energy from an endothermic reaction
what change in temperature would shift a system to the right?
- adding energy to an endothermic reaction
- removing energy from an exothermic reaction
when volume is decreased in an equilibrium system,
reaction wants to shrink, and therefor shifts to the side with less volume
when volume is increased in an equilibrium system,
reaction wants to expand, and therefor shifts to the side with more volume
why do combustion reactions not immediately occur (without the assistance of energy)?
because all reactions have a required activation energy/barrier
how to overcome the activation energy/barrier
either
- raise the temperature
- use a catalyst
a catalyst
lowers the height of the activation barrier/energy
enzymes
are biological catalysts
pH
- a way to express the concentration of H30+
- pH less than 7 is acidic
- pH of 7 is pure water
- pH greater than 7 is basic
when calculating pH
- the SF in [H3O+] is the # of decimal places for your pH level
- in reverse, the # of DP in your pH level gives you the # of SF in your concentration
list of strong acids
- HCl
- HBr
- HI
- HClO4
- HNO3
- H2SO4
list of weak acids
-HF
-HC2H3O2
-H2CO2
-H2CO3
-H2SO3
H3PO4
list of strong bases
anything that contains OH and is soluble
list of weak bases
- NH3
- C5H5N
- CH3NH2
- CH3CH2NH2
- HCO3-
oxidation state of elemental compound
always zero
oxidation state of ion
equal to its charge
relationship between sum of oxidation states and net charge of a molecule
they are equal
ex: h20 net charge is 0, and sum of its oxidation states is 0
oxidation state of alkali metals
+1
oxidation state of group alkaline earth metals
+2
oxidation state of fluorine
-1
oxidation state of hydrogen
+1, with exceptions like LiH, NaH, CaH2 (oxidation state of group 1 & 2 metals take precedent)
oxidation state of oxygen
-2
oxidation state of halides
-1
oxidation state of sulfur and its group members
-2
oxidation state of nitrogen and its group members
-3
order of precedence for H, O, F oxidation states
FHO
mnemonic for oxidation and reduction
LEO the lion goes GER
LEO: Loss of Electrons is Oxidation
GER: Gain of Electrons is Reduction
half reaction method
write out net ionic equation, then separate into reduction half reaction and oxidation half reaction and add electrons to each accordingly. then (if necessary) multiply each by an integer to make the # of electrons on each side of the “complete” reaction equal
