Ch 16 Acid-Base Equilibria
main molecules in arrhenius vs bronsted-lowry vs lewis?
-Arrhenius= hydrogen and hydroxyl -Bronsten-lowry= proton acceptor or donor -Lewis=donating and accepting lone pair
what is the relationship between [H3O+] and [OH−]? include equation
-The hydronium ion concentration, [H3O+], and hydroxide ion concentration, [HO−], are related through the equilibrium equation Kw=[H3O+][OH−]=1.0×10−14 where Kw is the ion-product constant for water, which is equal to 1.0×10^−14 at 25 ∘C. You should notice that the higher the [H3O+], the lower the [OH−]. The two are inversely related.
describe Lewis acids and bases
-a Lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor
Acid vs base as defined by Bronsted-Lowry
-acid: proton donor -base: proton acceptor
what is a Browsten-lowry acid vs Brossten-lowry base?
-acid=proton donor -base=proton acceptor
ionization of a weak acid in water is_
-an equilibrium process with an equilibrium constant Ka that can be used to calculate the pH of a weak acid solution
ionization of weak bases in water is_
-an equilibrium process with an equilibrium constant Kb that can be used to calculate the pH of a weak base solution
what is the effect bases have on acids?
-bases lowers the amount of acid -when mixed together, their characteristics disappear altogether
what are the names of the other two models for acids and bases beside arrhenius model?
-bronsted-Lowry model -Lewis model
what are the organic/biological acids and bases?
-fatty acids -amino acids -carboxylic acids
strong electrolytes
acids and bases are strong electrolytes, ionizing or dissociating completely in aqueous solutions
weak electrolytes
acids and bases are weak electrolytes and ionize only partially
according with Bronsten Lowry, what is an acid? what is a base?
an acid is any substance (molecule or ion) that can transfer a proton (H+ ion) to another substance, and a base is any substance that can accept a proton.
weak acids/bases
are weak electrolytes and ionize only partially
how acids are bases react? (how this is termed and include example of equation)
-Acids and bases react together to form a salt and water with loss of the characteristic acid/base properties -bases counteract acids -neutralization HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)
what is an arrhenius acid? (include equation)
-An Arrhenius acid is a substance that increases the concentration of H+ ions in water. HA(aq) ⇋ H+(aq) + A─(aq)
what is an arrhenius base? (include equation)
-An Arrhenius base is a substance that increases the concentration of OH- ions in water MOH(aq) ⇋ M+(aq) + OH─(aq)
what are the tree definitions to acids and bases?
-Arrhenius definition -Bronsted-Lowry definition -Lewis definition
explain what an oxoacid is and how acidity varies with oxoacids
-is an acid that contains oxygen. To be more specific, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bound to oxygen that can dissociate to produce the H+ cation and the anion of the acid. -For oxoacids, acid strength increases with the oxidation number of the central atom. If the oxidation number is the same, acid strength increases with the electronegativity of the central atom.
what the autoionization of water produces?
-produces small quantities of H3O+ and OH- ions
besides acids and bases, what else can serve as Browsten-Lowry acid or bases?
-salt solutions, ions of a soluble ionic compoind
what is produced with the autoionization of water?
-small quantities of H₃O⁺ and OH⁻
arrhenius deals mainly with _and bronsted-Lowry accepts_ (what kind of bases)
-strong bases -accepts weak bases
we categorize acids and bases as being either_
-strong electrolytes -weak electrolytes
what are the two categorizations of acids and bases?
-strong electrolytes -weak electrolytes
what are the characteristics of bases? (taste, feeling, how react with timus,what color gives to specific indicator)
-tastes bitter -feels slippery -turns litmus blue -turns phenotphthalein pink
what are the characteristics of acids? (taste, how act with skin, how react with metals, what releases, turns litmus to what, what color gives to specific indicator)
-tastes sour -stings skin -corrosive to metals -releases CO2 from carbonates -turns litmus red -turns phenophthalein colorless
how percent ionization of weak acids relates with concentration? why?
-the percent ionization of a weak acid increases as the concentration decreases. -This is true for most electrolytes. Due to interactions with water, some ions remain paired up in solution. The higher the concentration, the more formula units that remain paired up.
conjugated acid-base pair
-two species that differ by the presence or absence of a proton
Strong acids have _ conjugate bases, and very weak acids have _ conjugate bases.
-very weak -strong
what a pH less than 7 or greater than 7 indicate?
A pH less than 7 indicates that a substance is an acid, and a pH greater than 7 indicates that a substance is a base.
Acid-base reactions are _(think about Bronsten Lowry definition) reactions
Acid-base reactions are proton-transfer reactions
depending on concentrations, when a solution is acidic, neutral, basic?
Acidic solution: [H3O+]>[OH−]. Neutral solution: [H3O+]=[OH−]. Basic solution: [H3O+]<[OH−].
besides the pH, what is another way to determine basic, neutral, acid solution? (think about concentrations)
Acidic, neutral, and basic aqueous solution can be distinguished by the relative values of their [H3O+] and [OH−] concentrations
ions of soluble ionic compounds can serve as_
Bronsten-Lowry acids or bases
By the Brønsted-Lowry definition, how acids and bases are defined?
By the Brønsted-Lowry definition, acids are proton donors and bases are proton acceptors.
By the Lewis definition, how acids and bases are defined?
By the Lewis definition, acids are electron-pair acceptors, and bases are electron-pair donors.
carbonate with acid results in what?
CO2 release
Lewis model
Describes A/B behavior in terms of electron pair transfer.
Bronsted-Lowry model
Describes A/B behavior in terms of proton (H+) transfer.
Due to the autoionization of water, in any aqueous solution, how hydrogen ion concentration relates with hydroxide ion concentration? what is another way to express this? (pH)
Due to the autoionization of water, in any aqueous solution, the hydrogen ion concentration and the hydroxide ion concentration, [OH−], are related to each other by the Kw of water: Kw=[H+][OH−]=1.00×10^−14 Based on this relation, the pH and pOH are also related to each other as 14.00=pH+pOH
For any conjugate acid-base pair, how they relate? (think about specific equation)
For any conjugate acid-base pair pKa+pKb=14.00
when the definition of Bronsten-Lowry and Lewis are the same? when they are different? why? what are two examples?
For bases, the two definitions are equivalent such that all Lewis bases are Brønsted-Lowry bases and vice versa. However, it is possible to have a Lewis acid that is not a Brønsted-Lowry acid. This is because Lewis acids include molecules and cations that have a vacant valence orbital, regardless of whether they have a proton to donate. -Common examples of Lewis acids (that are not Brønsted-Lowry acids) are metal ions, such as Al3+ and Cu2+
explain how polar bond and acidity changes as go through same column (up toward down) and same row (left to right)
For binary acids of elements in the same group of the periodic table, the H−A bond strength decreases down the group, so acidity increases. For binary acids of elements in the same row of the periodic table, the polarity of the H−A bond increases from left to right (as the electronegativity of A increases), so acid strength increases.
Water ionizes by the equation: (include extent of ionization in pure water and dilute aqueous solutions)
H2O(l)⇌H+(aq)+OH−(aq) The extent of the reaction is small in pure water and dilute aqueous solutions.
In addition to the acid-dissociation constant, Ka, another measure of the strength of an acid is_. (2) include formula
In addition to the acid-dissociation constant, Ka, another measure of the strength of an acid is percent dissociation, determined Percent dissociation=([HA] dissociated/[HA] initial)×100% In addition to the acid-dissociation constant, Ka, another measure of the strength of an acid is percent ionization, determined by the following formula: Percent ionization=[HA] ionized/[HA] initial×100%
what are indicators?
Indicators are compounds that change color with pH. Most indicators are actually weak acids that are one color when protonated and another color when ionized
indicators usually change color over what range?
Indicators usually change color over a range of 1 to 3 pH units
what is the relationship between Ka and Kb? What is the consequence of this?
KW=Ka X Kb the stronger the acid, the weaker its conjugate base
how the equilibrium constant of weak acids and bases are related? how this applies to: the stronger the acid, the_its conjugate base
Ka and Kb are related by the relationship Ka X Kb= Kw hence, the stronger the acid, the weaker its conjugate base
how Kw is affected by temperature?
Keep in mind that, like all equilibrium constants, the value of Kw changes with temperature.
equilibirum constant for autoionization of water equation
Kw=[H3O+][OH-]
what is the equillibrium constant of autoionization of water? what defines?
Kw=[H₃O⁺][OH⁻] -it defines the relationship between H₃O⁺ and OH⁻ concentrations in aqueous solutions
why other definitions of acids and bases were devleoped?
Not all acids and bases fit the Arrhenius model, so others were developed
how pH is related to acidity?
Notice that acidity and pH are inversely related. The lower the pH, the more acidic a solution.
how pH and concentration of OH- are related with basicity?
Notice that basicity is directly related to both pH and [OH−]. The higher the pH, the more basic a solution. The higher the [OH−], the more basic the solution.
how Ka relates with percent dissociation? (include strong acids and weak acids in your explanation)
Percent dissociation increases with increasing Ka. Strong acids, for which Ka is very large, dissociate completely (100%). For weak acids, the percent dissociation changes with concentration.
how percent of ionization relates to Ka? how this applies to strong acids vs weak acids?
Percent ionization increases with increasing Ka. Strong acids, for which Ka is very large, ionize completely (100%). For weak acids, the percent ionization changes with concentration. The more diluted the acid is, the greater percent ionization.
what is the formula for percent ionization for bases?
Percent ionization=([OH−]equilibrium/[B] initial)×100%
what Kb value and ionization value will have strong bases?
Strong bases will have a higher Kb value. Similarly, strong bases will have a higher percent ionization value.
how Kb and ionization percent are for strong bases? weak bases?
Strong bases, for which Kb is very large, ionize completely (100%). For weak bases, the percent ionization changes with concentration. The more dilute the solution, the greater the percent ionization.
which two ions are central to the arrhenius definitions of acids and bases?
The H+ ion for acids and the OH- ion for bases
The degree to which a weak acid dissociates in solution is given by its _
The degree to which a weak acid dissociates in solution is given by its acid-ionization constant, Ka.
how the percent of dissociation changes with more diluted acids?
The more diluted the acid is, the greater percent dissociation.
the pH of a solution is related to what? include equation
The pH of the solution is related to the H3O+ ion concentration by the equation pH=−log[H3O+]
what is the pOH? include formula (include what is the meaning of "p" and how relates to pH)
The pOH of a solution is related to the OH− ion concentration of the solution. The "p" scale is used to express concentrations that are very small in magnitude. The hydrogen ion concentration is expressed in terms of pH. The formula for pOH is analogous to that for pH: pOH=−log[OH−]
how the strength of an acid can be determined by its polarity of bond?
The strength of an acid, HA, is often determined by the strength and polarity of the H−A bond. In general, a weaker and more polar bond leads to a stronger acid.
lewis acid vs base
a lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor
The degree to which a weak base dissociates is given by the _
base-ionization constant, Kb.
Chemical species whose formulas differ only by one proton are said to be _
conjugate acid-base pairs.
What the equilibrium constant of water defines?
defines the relationship between H3O+ and OH- concentrations in aqueous solutions
what the pH scale does?
describes the acidity and basicity of an aqueous solution
why the arrhenius model of acids and bases was limited?
it is limited because it was restricted to aqueous solutions
what acid is the highly reactive, extremely corrosive and dangerous to humans?
hydroflouric acid (HF)
proton
hydrogen without an electron H+
how is ionization of weak acids in water? (value that can describe this and what can be used to calculate)
ionization of weak acids in water is an equilibrium process with an equilibrium constant Ka, that can be used to calculate pH of a weak acid solution
how is ionzation of weak bases in water? (value that can be used to describe it and what can be used to calculate)
ionization of weak bases is an equilibrium process with an equilibrium constant (Kb) that can be used to calculate the pH of a weak base solution
explain how methyl red indicator works?
methyl red (pKa=5) appears red in its acidic form (HX) and yellow in its basic form (X−). This color change occurs gradually between pH=4 and pH=6. At any pH below 4, methyl red will appear red because there is significantly more HX than X− present. At pH=pKa=5, methyl red will be orange because there will be equal amounts of HX and X−. At any pH above 6, methyl red will appear yellow because there is significantly more X− than HX present. where X-is the base and HX is the acid
what a pH of 7 indicates?
neutral substance
How oxidation number and acid strength change as we increase the number of oxygen atoms in a compound?
oxidation number and acid strength both increase with the number of oxygen atoms.
what is the pH of basic solutions?
pH greater than 7
what the pH is? what indicates? include formula
pH is a logarithmic scale used to indicate the hydrogen ion concentration, [H+], of a solution pH=−log[H+]
what is the pH of acid solutions?
pH is below 7
The scale used for measuring the acidity or basicity of a substance is known as the _. It ranges _
pH scale from 0 to 14
what the addition of pH and pOH equals? include formulas
pH+pOH=14. −logKw=−log[H3O+]+(−log[OH−]) pKw=pH+pOH
pH of acid solutions
pH<7 (below)
pH of neutral solutions
pH=7
what is the pH of neutral solutions?
pH=7
pH of base solutions
pH>7 (greater than)
acids are corrosive to metals because is what kind of reaction?
single replacement reaction
water is a _acid
strong acid
strong acids/bases
strong electrolytes, ionizing or dissociating completely in aqueous solutions
what is the acid that is one of the world's largest volume chemicals?
sulfuric acid
what are two acids used industrially?
sulfuric acid (H2SO4) -Hydrofluoric acid (HF)
what does Kb tell us?
the degree to which a weak base reacts with H2O in solution is given by its base-ionization constant, Kb.
how the percent dissociation of a weak acid relates with concentration?
the percent dissociation of a weak acid increases as the concentration decreases.
what is the use of the pH scale?
to describe the acidity or basicity of an aqueous solution
conjugate acid-base pair
two species that differ by the presence or absence of a proton
stopped at pg 672 beginning,
wait for teacher to start class on this!
hydroflouric acid is what kind of acid?
weak acid