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107 Cards in this Set
- Front
- Back
arrhenius acid
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species that dissociates in water to make H+ ions
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arrhenius base
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species that dissociates in water to make OH- ions
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arrhenius definition is limited to _____ solutions
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aqueous (H2O)
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bronsted-lowry acid
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donates protons/hydrogen atoms
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bronsted-lowry base
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accepts protons/hydrogen atoms
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bronsted-lowry definition is not limited to ____ solutions
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aqueous
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conjugate acid-base pairs
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common with bronsted-lowry definition
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conjugate acid
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acid that donates a proton in the forward rxn
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conjugate base
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base that gains a proton in the backward rxn
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ex) label conj acid/base in
H3O+ --> H+ + H2O |
H3O+ = acid
H2O = conjugate base |
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Lewis acid
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electron pair acceptor
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lewis base
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electron pair donor
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lewis acids encompass all arrhenius and BL definitions, but not the other way around
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know this note
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lewis acids tend to show up as ____ in rxns
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catalysts
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nomenclature arrhenius acids
HF HBr HClO HClO2 HClO3 HClO4 |
hydrofluoric acid
hydrobromic acid hypochlorous acid chlorous acid chloric acid perchloric acid |
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HNO2
HNO3 |
Nitrous acid
Nitric acid |
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water can act as both a ____ and an _____, making it _____
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base; acid; amphoteric
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water can react with itself through a process known as ____
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auto-ionization
H2O + H2O --> H3O+ OH- |
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H3O+ =
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Hydronium ion
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water dissociation constant Kw =
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[OH-][H+] = 1e-14
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the value Kw changes only in reference to _____
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temperature
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at higher temperatures (other than 298K) the Kw value will be ____
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larger
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addition of H+ or OH- will only shift the equilibrium of the Kw equation, not change the Kw value itself!
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know this
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pH =
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-log[H+] or log[1/H+]
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pOH =
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-log[OH-] or log[1/OH-]
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pH + pOH =
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14
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pH less than 7 or pOH greater than 7 is _____
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acidic
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pH greater than 7 or a pOH less than 7 is ______
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basic
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pH of 7 =
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neutral
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estimating pH....
if given H+ = .00001 then.... |
pH = -log[1e-5] = 5
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estimating less easy numbers...
given Ka = 1.8e-5....what is the pH? |
log[1.8e-5] = 5 - log[1.8] = pH is between 4 and 5
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log[fraction < 1] =
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negative
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log[fraction > 1]
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positive
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strong acids + bases ____ dissociate into their ionic components in aqueous solutions
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completely
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dissociation of strong acids and bases can be considered to go to ______
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completion
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strong acids commonly encountered include (6)
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HCl
HBr H2SO4 HNO3 HI HClO4 |
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strong bases commonly encountered include
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NaOH
KOH OH- coupled with group I/II metal |
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pH scale at 25C or 298 ranges from...
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1-14
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strength of acid dependent upon concentrations, not chemical behavior
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know
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weak acids and bases only _____ dissociate in aqueous solutions
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partially
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weak acid formula
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HA + H2O ---> H3O+ + A-
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acid dissociation constant Ka =
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[H+][A-] / [HA]
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the smaller the Ka value (closer to 1e-14) the _____ the acid
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weaker
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the smaller the Ka value, the ____ it will dissociate
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less
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weak base formula
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BOH ---> OH- + B+_
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the smaller the Kb value, the ____ the base
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weaker
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the smaller the Kb value, the ____ it will dissociate
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less
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if Ka is < 1 then...
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weak acid
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if Kb is < 1 then...
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weak base
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weak bases are almost always amines
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know
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conjugate acid
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the acid FORMED when a base gains a proton
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conjugate base
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the base FORMED when an acid loses a proton
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in a conjugate acid/base pair formed from a weak acid, the conjugate base is generally stronger than the conjugate acid
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know
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strong acid will produce a ____ conjugate base
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weak
HCl --> Cl- |
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stong base will produce a ____ conjugate acid
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weak
NaOH --> H2O |
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HCO3- + H2O --> CO3^2- + H3O+
find the conj acid/base of forward rxn |
CO3^2- = conjugate base
H3O+ = conjugate acid |
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given: find H+ in a 2.0M solution of acetic acid CH3COOH with a Ka = 1.8e-5
EQ: CH3COOH --> H+ + CH3COO- |
Ka = [H+][CH3COO-] / [CH3COOH]
x^2 / 2 = 1.8e-5 ; --> x = 6e-3M |
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salt/ neutralization formation
EQ = |
HA + BOH --> AB + H2O
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combinations of acids/bases
1. HCl + NaOH --> NaCl + H2O 2. HCl + NH3 --> NH4Cl 3. HClO + NaOH --> NaClO + H2O 4. HClO + NH3 --> NH4ClO |
SA + SB
SA + WB WA + SB WA + WB |
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weak bases are not _____
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hydroxides
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product of SA + WB can react with water to form original weak base again
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know (pg 261)
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product of SB and WA can react with water to form original weak acid again
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know 262
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acid equivalent is ____
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1 mole of H+ ions
H2SO4 can create 2 equiv. |
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base equivalent is _____
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1 mole of OH- ions
Ca(OH)2 can create 2 equiv. |
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equivalent weight is the molecular mass / _____
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number of equivalents (n)
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amphoteric species
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-water
-hydroxides of Al, Zn, Pb, Cr -species that can act as oxidizing or reducing agents - |
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titration
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procedure used to determine the molarity of a known reactant in a solution
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titrations involve reacting a known volume of solution of unknown concentration (called the ____) with a known volume of solution of known concentration (called the _____)
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titrand; titrant
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in acid-base titration, the equivalence point is reached when....
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the number of acid equivalents in solution = the number of base equivalents added....vise versa
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titration and neutralization problems can use the following EQ:
NV = NV |
N = normalities(concentrations)
V = volumes volumes have to be in same units |
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the equivalence point does not need to be at pH = ____
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7
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equivalence point can be measure in 2 ways....
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1. use an indicator
2. graphical method |
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indicator and pH
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color changes when it reaches the END POINT; not the EQ. POINT
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indicators are weak organic acid/bases
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know
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indicators do ___ significantly alter the EQ. PT due to low concentrations
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NOT
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indicator must always be a ____ acid or ____ base than the acid/base titrated
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WEAKER; WEAKER
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the most useful combinations of acid-base titrations are....
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SA/SB
SA/WB WA/SB .... WA/WB are not usually accurate...lacks shape change indicating an EQ. PT --more gradual change |
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Strong Acid and Strong Base titration curve...draw it
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http://www.myoops.org/twocw/mit/NR/rdonlyres/Chemistry/5-111Fall-2005/F5E3B564-7D9C-4284-9FBB-5B9C224C4E5A/0/chp_titration.jpg
addition of acid or base at beginning has no significant change in the pH once pH reaches ~ 7, EQ PT at 7, sharp increase until basic pH reached. flat line since addition of base does not change pH |
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SA/SB and EQ PT vs End Pt
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equivalence pt is lower than the end point
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the equivalence point for a SA/SB curve is ____ at pH 7 for monovalent species(valence of 1)
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ALWAYS
ex) HCl is monovalent |
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Weak Acid and Strong Base titration curve...draw it
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http://www.chem.ubc.ca/courseware/pH/section14/ph2.jpg
addition of pH at beginning has effect on pH, increases until EQ pt above pH of 7 (since basic) then peters off with addition of base still having effect on pH |
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the EQ. pt for a WA/SB is ____ greater than pH 7 and _____ in nature
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ALWAYS; basic
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the initial pH of a WA/SB is generally ____ in comparison to a SA/SB initial pH (pH = 2)
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higher (closer to pH 4)
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WA/SB produces a stronger/weaker conjugate base and a stronger/weaker conjugate acid
choose |
stronger; weaker
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Weak base and Strong acid titration curve...draw it
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http://image.tutorvista.com/content/ionic-equilibrium/titration-curve-weak-base-strong-acid.gif
the initial pH is in the basic range initial addition of acid changes the pH quickly the EQ. PT is in the acidic range (<7) addition of more acid still affects pH after EQ PT |
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Weak base and strong acid will produce a stronger/weaker conjugate acid and a stronger/weaker conjugate base
choose |
stronger; weaker
makes pH < 7 |
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the EQ. PT for a WB and SA is always/never pH < 7 and is acidic/basic in natue
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always; acidic
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polyvalent acids and bases
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are not monovalent in nature...thus have multiple EQ. PTs depending upon the number of equivalents released
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ex) Na2CO3 + HCl --> HCO3- + NaCl
-the initial predominant species would be CO3/HCO3 -as more acid added, the predominant species would be CO3/HCO3 |
-CO3
-both |
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1. Na2CO3 + HCl --> HCO3- + NaCl
2. NaHCO3- + HCL --> H2CO3 + NaCl the flat part of the graph = |
EQ. Pt CO3- --> HCO3-
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2. NaHCO3- + HCL --> H2CO3 + NaCl
- after the EQ. PT, the predominant species are HCO3-/H2CO3 |
both in equal numbers
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2. NaHCO3- + HCL --> H2CO3 + NaCl
the second flat region, the predominant species is HCO3-/H2CO3 |
H2CO3 = all HCO3- converted to this
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2. NaHCO3- + HCL --> H2CO3 + NaCl
the second large change in pH is |
the 2nd EQ. PT
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the titrations of the acidic and basic amino acids will have 2/3 EQ. pts
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3
1 = titration of the COOH 2 = titration of amino acid 3 = acidic/basic side chain |
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buffer solution
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mixture of a weak acid and its salts(conjugate base + cation)
or mixture of weak base and its salts(conjugate acid and anion) |
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example of Acidic buffer
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CH3COOH + (Na+ + CH3COO-)
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basic buffer solution example
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NH3 + (NH4+ + Cl-)
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buffer solutions are capable of _____ changes in pH when small amts of acid/base are added
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resisting
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process of acidic buffer solution and NaOH addition
CH3COOH + H2O --> H3O+ + CH3COO- |
addition of NaOH --> Na+ and OH-
the OH- reacts with H+ to form H2O --> leads to shift in right to dissociate CH3COOH to form acid H3O+ |
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scenario with acidic buffer and HCl
CH3COOH + H2O --> H3O+ + CH3COO- |
the HCl --> H+ + Cl-
H+ reacts with CH3COO- to form CH3COOH (weaker acid) maintaining the pH -shifts EQ to the left |
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HCO3-/H2CO3 buffer most important with ____
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blood
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metabolic acidosis will cause the respiratory rate to increase/decrease and increase/decrease expulsion of CO2/H+ and will increase/decrease the pH
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increase
increase increase |
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blood pH is ....
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7.4
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henderson-hasselbach EQ
pH = pKa + log[conj. base]/[weak acid] |
know
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henderson-hasselbach EQ
pOH = pKb + log[conj. acid]/[weak base] |
know
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note: when [conj. base] = [weak acid], pH = pKa
note: when [conj. acid] = [weak base], pOH = pKb |
know
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if the ratio of the buffer components (1:1 --> 2:2) doesn't change, the pH of the buffer solution does not change....but what does change?
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buffering capacity
doubling the concentrations doubles the buffering capacity |