Unit Test 3: Ch.14 and part of 15 Flashcards
Arrhenius Definition of Acids & Bases?
Lewis?
Bronsted Lowry?
Produces H+ in solution, OH- in solution. Limited definition
e- acceptor, e- donor
proton donor, acceptor
conjugate acid base pairs?
rule?
every acid forms a conjugate base
every base forms a conjugate acid\
A strong acid/base forms a weak conjugate acid
A weak acid/base forms a stronger conjugate acid
formula for Ka?
HA -><- H+ + A-
Ka = [A-][H+]/[AH]
Strong acids ____ dissociate in an aq solution
completely
Titration
addition of a measured volume of base of known M into an acid to be analyzed. Base is titrant, acid is analyte.
equivalence point vs. endpoint
enough titrant has been added to react 1:1 w/ analyte. To indicate this we use indicator.
1 drop beyond that point
Normality (N)?
for a mono/di/triprotic acid in respect to molarity?
equivalents/Liter
= molarity
2* M
3*M
equivalent mass?
weight of acid used/# of acid equivalents
oxyacids? organic acids?
acidic proton attached to an oxygen
contains a carboxylic acid functional group. (COOH)
amphoteric? autoionization?
can behave like an acid or base
a rxn in which 2 like molecules react to form ions. Done by water often.
Kw? what does it mean/formula
1.0*10-14
for H2O ⇔ H+ + OH-
Kw = [H+][OH-]
formula for pH? pOH? relate them
this easy
rounding rule for pH?
the # of places after the decimal point in the pH equals # of sigfigs in concentration of H+
Calculating pH of strong acids
easy asf. Acids completely dissociate and you can easily calculate [H+] from this
practice calculating pH of weak acids…
problem #73a
interactive example 14.9
problem #83
5% rule for approximations?
(x/[Reactant]0)*100
if it is 5% or larger, solve quadratic!
% dissociation of weak acids…
formula?
for a given weak acid, % diss becomes ____ as acid dilutes more
and [H+] ____
[Amount dissociated]/[Initial concentration] * 100
interactive example 14.10
larger
decreases
problem #85b, d
Strong bases __ dissociate and are ___ electrolytes
completely, strong
list all strong acids and bases.
Acids: HCl, HBr, HI, H2SO4, HNO3, HClO4
Bases:
Group 1A: NaOH, KOH, LiOH, RbOH, CsOH (all group but not Fr)
Group 2: Ca(OH)2, Ba(OH)2, Sr(OH)2
Weak bases
General formula for base dissociation
Kb?
do not completely dissociate and form an equilibrium
B(aq) + H2O(l) ⇔ BH+(aq) + OH- (aq)
Kb = [BH+][OH-]/[B]
example 14.13
problem 109a
all of our weak base rxns will be reacting with water to produce BH+ which is the _____ and OH- which is the ____. This is called:
conjugate acid
conjugate base
hydrolysis (destruction/removal of water)
Calculating pH of a strong base
they fully diss., so we will do this the same way as a strong acid.
example 14.12
Ka * Kb = ___
pKa = ?
pKb = ?
pKa * pKb = ___ = ___
Kw = 1.0 * 10^-14
-log(Ka)
-log(Kb)
pKw = -log(Kw) = 14.00
Properties of salts that produce neutral solutions:
consist of cations of ___ bases and the anion of ___ acids and have 0 effect on [H+]. Reason why
strong, strong
because since strong acids and bases completely dissociate in water, if the cation binded to an OH- in the water or the anion binded to an H+ in water, it would quickly dissociate again
problem 133a
properties of salts that produce basic solutions
cation has ___ and whose anion is the conjugate base of a ___. Aqueous solution is basic
why?
sometimes you have to calculate Kb from ___ and ___ if you have the ___ from the acid in the products side, and not the Kb from your anion from the salt
neutral properties (strong base), weak acid
cation will bind to an OH and quickly dissociate. Conjugate base of a weak acid will bind to an H+ and hold onto it longer, as weak acids hold onto their proton more and remove [H+], making solution basic.
example 14.18
problem 133b
Ka, Kw, Ka
Effect of structure on acid-base behaviors
A molecule containing H+ will donate if its bond is ____ due to ____
HF is a very ___ molecule, but will not donate due to its ___ bond
CH4 will not donate due to ____ and ___
for oxyacids, acid strength ___ as oxygens on central atom increases. This is because___
polar, electronegativity differewnce
polar, strong
strong bond and non-polarity
increases. they pull away electrons from the OH.
table 14.7, 14.8, chapter 14.9 in general
for polyprotic acids
the first dissociation makes the ____, simplifying the problem greatly
however, know how to calculate the concentrations of the anion w/ no H+
example 14.15
there are cases where you do have to calculate the [H+] contributed in the 2nd dissociation. This only happens with ____. This is due to _____. However, you only have to do it in ___ solutions since % dissociation goes up
significant [H+] contribution
sulfuric acid. High solubility, only diprotic strong acid we have to know. dilute.
ex 14.16, 14.17
problem 126, 125
acidic metal salts
they do not directly act as an acid, but it will dissociate to form ___. the hydrated ion can act as an ____. provide example and write equation
in the example provided, the metal ___ the OH bonds in the H2O, making the hydrogens more acidic (refer to 14.9) than those in free H2O. Typically, the higher the charge, the ___ the hydrated ion acidity
hydrated ions. weak acid.
Ex: AlCl3 -> Al(H2O)63+ and 3Cl-
Al(H2O)63+(aq) ⇔ Al(OH)(H2O)52+(aq) + H+(aq)
solve js like a weak acid!
polarizes, stronger
example 14.20, problem 143/144
Salts that produce acidic solutions:
anion is ___ and cation is ___
not a base/conjugate base of a strong acid
conjugate acid of a weak base
understand how to calculate Ka from Kb and vice versa.
Example, calculate Ka of NH4+ from Kb of NH3
pretty easy
Ka*Kb = Kw
rearrange as needed
use for conjugate acids & bases when placed in aqueous solutions
Salts w/ acidic and basic ions…
cation is conjugate acid of ____, and anion is conjugate base of ____
to determine whether dissolution makes solution acidic or basic…
a weak base
a weak acid
acidic if Ka of acid formed by salt is larger than Kb of base formed by salt
basic of Kb is larger than Ka
neutral if they are equal
problem 146
memorize table 14.6
when adding a common ion to an acid or base the equilibrium shifts ____
left
common ions in acidic or basic solutions ___ the percent dissociation
decrease
Buffer solution
weak acid & its conjugate base solution, resistant to pH changes when SMALL amounts of a strong acid or base are added
buffer capacity
amount of acid or base the buffer can neutralize before pH begins to change to an appreciable degree
Two ways to make buffers
weak acid w/ a salt of conjugate base
weak base w salt of conjugate acid
how would CH3COOH -><- CH3COO- + H+ act as a buffer?
if OH- is added, CH3COOH + OH- -> H2O + CH3COO-
if H+ is added, CH3COO- + H+ -> CH3COOH
interactive examples 15.2 and 15.3
henderson - hasselbach equation (do not need to memorize)
what is it used for?
43
for HA -><- A- + H+
pH= pKa + log([A-]/[HA])
used to calculate pH of a solution w/ known [A-] and [HA], useful for buffering solutions
look at interactive examples?
