Chapter 17 - Acid, Bases, and Salts
Strong bases are
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
How does a conjugate acid differ from its conjugate base?
A conjugate base may be positively charged, neutral, or negatively charged. The conjugate acid of a neutral base will have a charge of +1. The conjugate acid has one more H than its conjugate base.
weak acids examples
Any organic acid, H₂O, HF, HCN
Why is it easy to ionize initially for polprotic acids?
At first, it is easy to remove an H+ from a polyprotic acid, since it is neutral. However, it becomes increasingly difficult to remove more and more H+ ions from a polyprotic acid because it gains a more negative charge everytime an H+ is removed, and it is very difficult to remove H+ ions from negative ions.
A Bronsted-Lowry base is a proton _____. A Bronsted-Lowry base must contain an available_______pair of_______in its formula in order to form a_____bond to H+.
Blank 1: acceptor Blank 2: lone , nonbonded, nonbonding, non-bonding, non-bonded, unshared, or unbonded Blank 3: electrons Blank 4: covalent, single, or sigma
An acid can be defined as a substance that loses one or more H+ ions when dissolved in water. An H+ ion is a hydrogen atom that has lost a(n) and is therefore just a(n) . The H+ ion is not an isolated ion, but interacts strongly with H2O to produce the ion, which has the formula H3O+.
Blank 1: electron Blank 2: proton, hydron, or cation Blank 3: hydronium or H3O+
The strength of an acid is measured by its tendency to _____and produce ______ ions in aqueous solution.
Blank 1: ionize or dissociate Blank 2: hydrogen, hydronium, H+, or H3O+
The two factors that influence the extent of ionization of an acid are the _______and _______ of the HX bond, where HX is the general formula of an acid.
Blank 1: strength, bond strength, or weakness Blank 2: polarity
Which of the following statements correctly describe carboxylic acids, represented by the general formula RCOOH?
Carboxylic acids are organic acids represented by the general formula RCOOH. As R changes, the strength of the acid changes. Carboxylic acids are weaker acids than hydrohalic acids such as HCl.
Which of the following formulas can be used to represent a hydrogen ion in aqueous solution?
H3O+ H+ The hydrated species H3O+ is often shown more simply as H+.
Strong acids are
HCl, HBr, HI, HNO3, H2SO4, HClO4, HClO3
The strength of the hydrohalic acids from weakest to strongest
HF, HCl, HBr, HI and HAt
hydrohalic acids
In chemistry, hydrogen halides are diatomic, inorganic compounds that function as Arrhenius acids. The formula is HX where X is one of the halogens: fluorine, chlorine, bromine, iodine, or astatine.
When is the hydronium ion concentration ignored?
In concentrated solutions the hydronium ion concentration from the ionization of water can be ignored because the amounts or negligible. But in dilute solutions cannot be ignored.
How do we determine oxyacid strength?
In general, the relative strength of oxyacids can be predicted on the basis of the electronegativity and oxidation number of the central nonmetal atom. The acid strength increases as the electronegativity of the central atom increases. The strength of an oxyacid decreases with the oxidation state of the element.
Select the statement that correctly explains why it is reasonable to assume that for a weak acid [HA] at equilibrium is approximately equal to [HA]initunder most circumstances.
Most molecules of the weak acid remain unionized at equilibrium.
Weak bases include
NH3, amines, and anions of weak acids
Arrhenius acid
Produces H+ ions when dissolved in water
Arrhenius base
Produces OH- ions when dissolved in water
Which of the following statements accurately describe Bronsted-Lowry acid-base reactions?
Some species can act as either an acid or a base depending on the other species present. The reactants and products contain an acid and a base.
T or F the hydronium ion is the strongest ion that can exits in an aqueous solution?
True
T or F The solution of a strong acid will have a negligible concentration of unionized HA molecules.
True A strong acid ionizes completely into ions, leaving few or none of the intact HA molecules in solution
conjugate pairs
Two species that differ by one proton
When calculating the pH of a weak acid or weak base solution, we assume that the [H3O+] or [OH-] due to ionization is negligible compared to the concentration of acid or base. When is this assumption justified?
When the acid/base shows less than 5% ionization
In equilibrium calculations involving a weak acid it is reasonable to approximate that _____.
[HA]equilibrium ≈ [HA]initial It is acceptable to assume [HA]equilibrium = [HA]initial - x ≈ [HA]initial = [HA]initial when x is less than 5% of [HA]initial.
Ka
acid ionization constant
polyprotic acid
an acid that can donate more than one proton per molecule
Oxoacids
an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.
carboxylic acid
an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is R−COOH
Where does pH come from?
auto ionization
Kb
base dissociation constant
Factors that impact acid strength
charge Strong acid = lower charge Weak acid = higher charge bond length Strong acids = longer bond (weaker bond, easier to remove H+) Weak acids = shorter bond (stronger bond, harder to remove H+) electronegativity Strong acids = more electro neg Weak acids - less electroneg (share e- more equally which means stronger bond_
In a Bronsted-Lowry acid-base reaction, the acid reacts to form its _____ and the base will form its _____.
conjugate base; conjugate acid
Characteristics of strong acids and bases
dissociates 100% into electrolytes, good conductor, no equilibrium, conjugates have no measurable strength
Characteristics of weak acids and bases
dissociates partially (<100%) into only a few electrolytes, poor conductors (but still conducts a little), equilibrium process, conjugates can act as bases/acids
A Bronsted-Lowry acid is a proton _____ and must therefore contain at least one ionizable _____ atom in its formula.
donor; hydrogen
T or F When we dilute something the number of moles changes?
false, only molarity changes
Basic pH
greater than 7
Oxoacids have the general formula illustrated, where the number of bonds to the central element E can vary. For the same element E, acid strength will _____ as the number of O atoms increases. For the same number of O atoms, acid strength increases as the _____ of element E increases.
increase; electronegativity As the atomic size of element E increases, its electronegativity generally decreases. Acid strength increases with increasing electronegativity and therefore decreases as atomic size increases.
Acidic pH
less than 7
For solutions with the same initial concentration of acid HA, the smaller the value of Ka, the ______ the % ionization and thus the ______ the acid.
lower, weaker A small Ka indicates a weak acid with low % ionization.
Does percent ionization matter for both weak and strong acids?
no, only weak acids since strong acids have 100% ionization
carboxylic acid is an inorganic or organic acid
organic
In carboxylic acids, the ionizable proton is the one bonded to
oxygen
Neutral pH
pH of 7
Bronsted-Lowry base
proton acceptor
Bronsted-Lowry acid
proton donor
Acid ionization is represented by the general equation HA + H2O (l) ⇌ H3O+ (aq) + A- (aq) For a strong acid the equilibrium lies far to the _____ and [H3O+] is much _____ than [HA]. For a weak acid, on the other hand, the equilibrium lies far to the _____ and [H3O+] is much _____ than [HA]. Multiple choice question.
right, higher, left, lower
the higher the Ka, the ______ the acid
stronger equilibrium lies to the right
The higher the kb
stronger base and equilibrium lies to the right
conjugate acid
the particle formed when a base gains a hydrogen ion
conjugate base
the particle that remains when an acid has donated a hydrogen ion
the lower the Ka, the _____ the acids
weaker equilibrium lies to the left