Chapter 18 prin of chem
form their conjugate base and conjugate acid
A Bronsted-Lowry acid-base reaction occurs when an acid and a base react to _________.
Equilibrium constant Increases Decreases Water Increases Decreases Ksub-w is constant
A change in concentration shifts the equilibrium position but does not change the _____. If some acid is added, [H₃O⁺] ___ and [OH⁻] ___ as the ions react to form ___ and if some base is added [OH⁻] ___ as [H₃O⁺] ___. In both cases, the value of ___ is ___ if temp does not change.
Autoionization of water Product Ksub-a of the acid
A key relationship exists between the Ksub-a of HA and the Ksub-b of A⁻: the sum of the two dissociation reactions is the _________. Ksub-w is the ___ of the individual equilibrium constants of Ksub-a and ksub-b. This relationship allows us to find ______ in a conjugate pair given Ksub-b of the base.
High K Low pK High pK
A low pK corresponds to a ___ K. A reaction that reaches equilibrium with mostly products present has a ______ while one that has mostly reactants present at equilibrium has a ______.
Ksub-b that is a stronger base
A lower pKsub-b indicates a ___ that is a ___ base.
Form a weaker acid and weaker base →weaker base+weaker acid Two bases in which NH₃ Weaker acid NH₄⁺
A reaction proceeds to the greater extent in the direction in which a strong acid and stronger base _________: Stronger acid+stronger base_________. In H₂S+NH₃→HS⁻+NH₄⁺, you can think of the process as a competition for the proton b/t the ______ in which ___ wins and becomes the _________.
Neutral solution Ions do not react with water
A salt consisting of the anion of a strong acid and the cation of a strong base yields a ______ b/c the _________.
Basic solution Weak base Does not react
A salt consisting of the anion of a weak acid and the cation of a strong base yields a ______ because the anion acts as a ______, and the cation ______.
Acidic solution Weak acid Does not react Acidic solution Weak acid Does not react
A salt consisting of the cation of a weak base and the anion of a strong acid yields an ______ b/c the cation acts as a ______, and the anion _________. A salt consisting of a small, highly charged metal cation and the anion of a strong acid yields an ______ b/c the cation acts as a ___, and the anion ______.
Stronger conjugate base Conjugate base is holding it too strongly Reacts with a stronger base Weaker conjugate base and a weaker conjugate acid.
A weaker acid has a _________: the acid can't give up its proton very readily b/c its _________. A reaction proceeds to the right if an acid _________ (list from pg 591) b/c this combination produces a _________.
Proton donor Donates an H⁺ ion H All Arrhenius acids Proton acceptor Accepts an H⁺ ion Lone pair of electrons to bind H⁺ Are not Contain Bronsted-Lowry base OH⁻
According to the Bronsted-Lowry acid-base difinition, an acid is a ______, any species that _________. An acid must contain ___ in its formula. _________ are Bronsted-Lowry acids. A base is a ______, any species that _________. A base must contain a _________. Bronsted-Lowry bases ___ Arrhenius bases, but all Arrhenius bases ___ the Bronsted-Lowry base ___.
Donates Accepts Amphiprotic
Acid ___ a proton to water Base ___ a proton from water H₂O acts as a base in once case and as an acid in another, making it ___.
Large range Fraction of HA
Acid-dissociation constants of weak acids have a ______ of magnitudes and give us benchmarks Ksub-a values that lets us know the _________ molecules that dissociate into ions.
Strength Dissociation
Acids and bases are classified by their ___, the amount of H₃O⁺ or OH⁻ produced per mole of substance dissolved, so by the extent of their ___ into ions.
Polyprotic acids Ksub-a
Acids with more than one ionizable proton are ______. Each dissociation step has a different ___.
Low [OH⁻] Low [H₃O⁺]. Acidic and basic Magnitudes of [H₃O⁺] and [OH⁻]
All acidic solutions contain a ______, and all basic solution contain a ______. The equilibrium nature of autoionization allows us to define ___ and ___ solutions in terms of relative ___ of ___ and ___
O atom Involved EN O atoms around E
All oxoacids have the acidic H atom bonded to an ______, so bond length is not ___. Two other factors determine the acid strength of oxoacids: the ___ of the central nonmetal (E), and the number of _________.
Weak acids Weak base HF and OH⁻ OH⁻ and H₃O⁺ [OH⁻]from F >> [H₃O⁺]from H₂O
Another large group of Bronsted-Lowry bases consists of anions of ______. When NaF dissociates completely to yield NA⁺and F⁻. The Na ion behaves as a spectator ion, while some F⁻ reacts as a ______ to produce small amounts of ___ and ___. The two species that affect the acidity out of Na⁺, HF, H₂O, H₃O⁺, F⁻, and OH⁻, are ___ and ___, IN this case ___ >> ___, so the solution is basic
Acid-base indicators pH meter
Are organic molecules whose colors depend on the acidity of solution in which they are dissolved. A ______ measures [H₃O⁺] by means of two electrodes immersed in the test solution.
Same Hydrogen ion and hydroxide ion hydrated spectator ions ∆H°rxn.
Arrhenius suggested that the enthalpy change is always the same b/c the reaction is always the ___: ______ and a ______ form water, which is ∆H°rxn is -55.9 kJ, and the dissolved salt that forms along with the water exists as _________ and does not affect ___.
E-H bond H⁺
As E becomes larger, the ______ becomes longer and weaker, so ___ comes off more easily.
Increases Percent HA dissociated lower
As the initial acid concentration decreases, the percent dissociation of the acid ___. Don't confuse the concentration of HA dissociated with the ___ HA ___. The concentration, [HA]sub-dissoc, is ___ in the diluted HA solution b/c the actual number of dissociated HA molecules is smaller.
Inverse Lower [OH⁻] Lower [H₃O⁺] Present
Autoionization of water affect aqueous acid-base chemistry in two major ways: 1. A change in [H₃O⁺] causes an ___ change in [OH⁻], and vice versa. Higher [H₃O⁺]→___ & higher [OH⁻]→___ 2. Both ions are ___ in all aqueous systems.
Acids and bases Strong electrolytes Weak electrolytes
B/c ___ and ___ are electrolytes, their strength correlates with electrolyte strength: ______ dissociate completely and ______dissociate slightly.
Multiply ksub-c by [H₂O]² Ion-product constant for water, Ksub-w Ksub-c[H₂O]²=Ksub-w=[H³O]⁺[OH⁻]=1.0E-14 at 25°C
B/c the concentration of H₂O (55.5M) remains essentially constant, we ___ Ksub-c by ___ to obtain a new equilibrium constant, the _________: ___=___=___
10 times 100 times Opposite negative antilog
B/c the pH scale is logarithmic, a solution of pH 1.0 has an [H₃O⁺] that is ___ times higher than that of a pH 2.0 solution, ___ times higher than that of a pH 3.0 solution and so on. To find the [H₃O⁺] from the pH, you preform the ___ arithmetic process: get the ______ of pH
Arrhenius acid-base definition Acid Base
Classifies acids and bases in terms of their formulas and behavior in water: An ___ is a substance with H in its formula that dissociates in water to yield H₃O⁺; A ___ is a substance with OH in its formula that dissociates in water to yield OH⁻.
Reactants Products Neutral, cationic, or anionic Acid or a base (amphiprotic) Species reacting
Each reaction has an acid and base as ___, and the conjugate acid-base pairs as ___ Acids and bases can be _________ The same species can be an ___ or a ___, depending on the other ______.
~10% ~.3% ~.001% Lower the percent dissociation of HA Weaker the acid→Lower % dissociation HA→Smaller Ksub-a
For a weak acid with a relatively high Ksub-a, a 1M solution has ___ of the HA molecules dissociated. For a weak acid with moderate Ksub-a, a 1M solution has ___ of the HA molecules dissociated. For a weak acid with a relatively low Ksub-a, a 1M solution has a ___ of the HA molecules dissociated For solutions of the same initial HA concentration, the smaller the Ksub-a, the ___ the _________. ___→___→___
Increases with number of O atoms (or O.N. of Central nonmetal)
For oxoacids with different numbers of O atoms, acid strength increases with _________.
Electronegativity of E
For oxoacids with the same number of O atoms, acid strength increases with the _________.
Donates Simultaneously accepts Proton-transfer Gaseous solutions, nonaqueous solutions, heterogeneous mixtures, and in aqueous solutions
From the Bronsted-Lowry perspective, an acid-base reaction occurs when one species ___ a proton and another species ______ it, which makes it a ___ process. Can occur in ___, ______, ______, as well as in ______.
Acid-base reaction Covalent bonds Adduct Lewis acid
Hydration of a metal ion is itself an ______ as electron pairs on the O atoms of H₂O molecules form ______, the hydrated cation is the ___, so a metal ion acts as a ______ when it dissolves in water.
pOH: pOH=-log[OH⁻] pK=-logK Higher pOH
Hydroxide ion concentration can be expressed as ___: ___=___ Equilibrium constants can be expressed as ___: ___=___ Acidic solution have a ______ than basic solutions
Relative acid strength (Ksub-a) and base strength (Ksub-b)
If a salt consists of a cation that is a weak acid and an anion that is a weak base, the overall acidity of the solution depends on the _________ of the separated ions.
Amine
If one or more of the H atoms in ammonia is replaced by an organic group, an ___ results.
Concentration [H₃O⁺]=ksub-w/[OH⁻]
If you know the value of Ksub-w at a particular temp and the concentration of one of the two ions, you can find the ___ of the other: [H₃O⁺]=___
Conjugate acid-base pair Conjugate base Conjugate base Conjugate acid
In Bronsted-Lowry terminology, H₂S (reactant) and HS⁻ (product) and species of similar reactions, are a _________. HS⁻ is the ______ of the acid H₂S. So every acid has a ______, and every base has a ______.
Amphiprotic Ksub-a and Ksub-b Same specie, the anion
In a salt that has a cation from a strong base and the anion that comes from a polyprotic acid with one or more ionizable protons still attached, the anions in this case are ___. To determine the overall acidity of their solution, we compare the magnitudes of ___ and ___ but of the ______.
> = <
In an acidic solution, [H₃O⁺] ___ [OH⁻]. In a neutral solution, [H₃O⁺] ___ [OH⁻] In a basic solution, [H₃O⁺] ___ [OH⁻]
p-scale Common logarithm pH, the negative logarithm pH=-log[H₃O⁺]
In aqueous solutions, [H₃O⁺] can vary from about 10M to 10E-15M. To handle numbers with negative exponents easily, we convert them to positive numbers using a ___, the negative of the ______ of the number. Applying this numerical system to [H₃O⁺] gives ___, the ______ of [H⁺], or [H₃O⁺]: ___=___
Neutralization ∆H°rxn is -55.9 kJ
In the Arrhenius sense, ___ occurs when the H⁺ from an acid and the OH⁻ from the base form H₂O.. Key point about this is that no matter which strong acid and strong base react, and no matter which salt results ______ per mole of water formed
Temperature dependent Right Higher Larger Stronger acid→higher [H₃O]⁺→larger Ksub-a
K-a is a number whose magnitude is ______ and tells how far to the ___ the reaction has proceeded to reach equilibrium, so the stronger the acid, the ___ [H₃O]⁺ is at equilibrium, and the ___ the Ksub-a: ___→___→___
Electron-rich nitrogen N atom with a lone electron pair Ammonia and Amines
Many compounds with an ______ atom are weak bases. The common structural feature is an ___ atom with a ______: ___ and ___.
Brackets Species comes from or when it occurs in the reaction process Species at equilibrium
Molar concentration is indicated with ___. A subscript refers to where the _________ or when it _________. A bracketed formula wit no subscript represents the molar concentration of the _________
Double bond Partially positive end pi bond
Molecules with a _________ also function as Lewis acids. An electron pair on the Lewis base approaches the _________ of the double bond to form a new bond in the adduct, as the _________.
Each H₂O 1 in 555 million water molecules
One H₃O⁺ ion and one OH⁻ ion form for ______ molecule that dissociates. Since pure water has a concentration of about 55.5M, these equilibrium concentration are attained when only ___ in ________ dissociates reversibly into ions.
[HA]sub-dissoc/[HA]sub-init
Percent HA dissociated=____
Proton acceptor (or donor) An acid dissolves in water
Since water acts as a ______, an acid-base reactions occurs even when just ____________.
Ksub-a1>>Ksub-a2>>Ksub-a3 H⁺ ion Singly charged anion neutral molecule
Strength of polyprotic acids: K___>>K___>>>K___ This trend occurs b/c it is more difficult for an ______ to leave a _________ than to leave a ______ and so on.
Completely no longer present 0 Large >>1
Strong acids dissociate ___ into ions in water. In a dilute solution of a strong acid, HA molecules are _________ [H₃⁺O⁺]≈[HA]sub-int. Meaning, [HA] at equilibrium ≈ ___, so the value of Ksub-c is extremely ___. At equilibrium, Qsub-c=Ksub-c ______
Classes of acids Lewis acids Accept an electron pair in reactions Lewis acid
The Lewis acid-base definition expands the _________ b/c many species such as CO₂ and Cu²⁺ that do not contain H in their formula are ______ b/c they _________. So the proton itself is a ______ b/c it accepts the electron pair donated by a base.
Donates an electron pair Accepts an electron pair
The Lewis acid-base definition holds that a base is any species that _________ to form a bond and an acid is any species that _________ to form a bond.
Smaller Neglect it Neglect the change in its concentration
The [H₃O⁺] from the autoionization of water is so much ___ than the [H₃O⁺] from the dissociation of HA that we can ______. A weak acid has a small Ksub-a. Therefore, it dissociates to such a small extent that we can _________ to find its equilibrium concentration
Hydrated metal ion transfers an H⁺ ion to water. Small and highly charged High charge density O-H bonds of the bound water molecules H⁺ is released
The aqueous solutions of certain metal ions are acidic b/c the _________. If the metal ion, Mⁿ⁺, is _________, its ______ density withdraws sufficient electron density from the ______ of the bound ______ that an _________.
Fewer, more More, fewer
The conjugate base has one ___ H and one ___ minus charge than the acid. The conjugate acid has one ___ H and one ___ minus charge than the base.
Electron density E-H bond becomes more polar H⁺ O atom of a water molecule
The electronegativity of the nonmetal E determines the trend. From left to right, as E becomes more EN, it withdraws ______ from H, and the ______ becomes more ___. As a result, ___ is pulled away more easily by an _________.
Accepts a proton from H₂O Ksub-c=[BH⁺][OH⁻]/[B][H₂O] [H₂O] Ksub-b=[BH⁺][OH⁻]/[B]
The equilibrium system of a weak base (B) as it dissolves in water: B _________, which acts as an acid, leaving behind an OH⁻ ion. This general reaction for a base in water is described by the equilibrium expression Ksub-c=___. We thin incorporate ___ in the value of Ksub-c and obtain ______: ___=___
Lower the [H₃O⁺] Lower pH (higher [H₃O⁺]) 7.00 and neutral < >
The higher the pH, the _________. An acidic solution has a ___ pH than a basic solution. In pure water, [H₃O⁺] is 1.0E-7, so its pH is ___ and ___ pH of an acidic solution ___ 7.00 pH of an basic solution ___ 7.00
3A elements boron and aluminum React to complete that atom's octet
The most important of the electron-deficient Lewis acids are compounds of the Group _________. These compounds have fewer than eight electrons around the central atom, so they _________. Such as BF₃+NH₃⇌BF₃-NH₃
Reflects the precision Decimal point
The number of sig figs in pH _________ with which the concentration is known. The number of sig figs in the concentration equals the number of digits to the right of the ______ in the pH value.
What you want to find 1. Balanced equation and Ksub-a 2. x x=[HA}sub-dissoc [H₃O⁺] and [A⁻] 3. Reaction table 4. Assumptions 5.Ksub-a expression 6. 5% test Quadratic formula
The problem-solving approach. Start with what is given in the problem and move toward what _________: 1. Write the ___ and the ______; these tell you what to find 2. Define __*_ as the unknown change in concentration that occurs during the reaction. Frequently, ***=___, the concentration of ___ that ___, which, through the use of certain assumptions, also equals ___ and ___ at equilibrium. 3. Construct a ______ that incorporates *** 4. Make ___ that simplify the calculations 5. Substitute the values into the ______, and solve for *** 6. Check that the assumptions are justified with ______. If not justified, use the ______ to find ***.
Adduct A+:B ⇌ A-B
The product of a Lewis acid-base reaction is an ___, a single species that contain a new covalent bond.
Acidity or basicity of a solution
The relative concentrations of HA and A⁻ determine the _________
HCl, HBr, and HI O atoms -Ionizable protons
The strong Hydrohalic acids are? Strong Oxoacids are in which the number of ______ exceeds the number of ______ by two or more.
pKsub-w 14.00 Interrelated
The sum of pH and pOH is ___ for any aqueous solution at any temp, and * equals ___ at 25°C Becuase * is constant, pH, pOH, [H₃O⁺], and [OH⁻] are ___.
Many more HF O or to a halogen, such as HCN and H₂S O atoms equals or exceeds the number of ionizable protons Carboxylic acids (RCOOH)
There are ______ weak acids than strong ones, four types are: 1. They hydrohalic acid ___ 2. Acids in which H is not bonded to ___ or to a ___, such as ___ and ___. 3. Oxoacids in which the number of ______ equals or exceeds the number of ______ by one 4. ______ (have genral formula ___)
Ksub-a Ksub-a and some concentrations
There are two types of equilibrium problems involving weak acids and their conjugate bases: Given equilibrium concentrations and then find ___, or given___ and ______ and then find other equilibrium concentrations.
Electronegativity E-H bond
Two factors determine how easily a proton is released from a nonmetal hydride: The ___ of the central nonmetal (E), and the strength of the _____.
Autoionization (self-ionization)
Water dissociates very slightly into ions in an equilibrium process known as ___. Ksub-c=[H₃O⁺][OH⁻]/[H₂O]²
O²⁻ or OH⁻ Most reactive metals M(metal)=Group 1A metals and Ca down from Group 2A
Water-soluble compounds containing ___ or ___ ions are strong bases. The cation are usually those of the _________. Where M equals ___ and __ down from ___.
Concentrations change to a significant extent Ksub-c=([H₃O]⁺[A⁻])/([HA][H₂O]) H20 Constant Ksub-C by [H₂O] Acid-Dissociation constant (Acid-ionization constant) Ksub-a Ksub-c[H₂O]=Ksub-a=([H₃O]⁺[A⁻])/([HA])
We write a specific equilibrium constant for acid dissociation that only includes species whose _________. The equilibrium expression for the dissociation of a general weak acid (HA) in water is ___=___, but since ___ is a pure liquid, which is essentially ___ when HA dissociates, we simplify the equilibrium expression by multiplying ___ by ___, giving us a new equilibrium constant called the ______ and is ___=___=___
Slightly Undissociated << ≈ Small (Qsub-c = Ksub-c << 1)
Weak acids dissociate ___ into ions in water. In a dilute solution of a weak acid, the great majority of HA molecules are ___. Thus, [H₃O]⁺___ [HA]sub-init and [HA]sub-eq ___ [HA]sub-init, so Ksub-c is very ___.
is a much weaker base than water. Hydrated Hydrated React
When a strong acid dissolves, the reaction goes to completion b/c the anion of a strong acid _________. The anion is ___, but it does not react with water. A strong base dissolves completely, and the cation is ___, but it is not small and charged enough to ___ with water.
Conjugate base A⁻ and the Conjugate acid H₃O⁺ Stronger acid Stronger base Much weaker base
When the a strong acid HA dissolves in water, it completely transfers an H⁺ to the base, H₂O, forming the _________ and the _________. HA is a ______ than H₃O⁺, and H₂O is a ______ than A⁻. Thus, with a strong HA, H₂O wins the competition for the proton b/c A⁻ is a ______. The only acidic species that remains in strong-acid solutions is H₃O⁺.
Discrete OH⁻ ions Discrete H⁺ ions Covalently bonded H atoms
While Arrhenius bases contain _________ in their structures, Arrhenius acids never contain _________. Instead they contain _________ that ionize when the molecule dissolves in water.
Wins Stronger base
With weak acids such as HF, the A⁻ ___ the competition b/c it is a ______ than H₂O.
Water Participate in the reaction H-bonded species H(H₂O)sub-n⁺ Charge density Lone electron pairs O Hydronium ion, H3O+
___ is the product in all reactions b/t strong acids and strong bases. Furthermore, whenever an acid dissociates in water, solvent molecules _________: water molecules surround the proton to form _______ with the general formula ___. B/c the proton is so small, its ______ is very high, so it attracts water very strongly. The proton bonds covalently to one of the _________ of a water molecule's ___ atom to from a ___, which forms H-bonds to several other water molecules to give species such as H₇O₃
pKsub-w=pH+pOH=14.00
pKsub-w=___.
