Vocabulary
Describe an Arrhenius acid and an Arrhenius base.
Arrhenius acid: substances that produce H+ ions in water
Arrhenius base: substances that produce OH- ions in water
The hydrogen sulfite ion is amphoteric. Write an equation for the reaction of HSO3- with water in which the substance acts as an acid.
In order for HSO3- to acid as an acid, it must donate a proton to H2O. After donating a proton, it becomes SO32- and H2O becomes H3O+ upon accepting a proton.
HSO3- (aq) + H2O (l) <--> SO32- (aq) + H3O+ (aq)
What is the equilibrium constant expression for the autoionization of water?
Kc = [H3O+][OH-]
Calculate the concentration of H+ (aq) in a solution in which [OH-] is 0.010 M.
[H+][OH-]=1.0x10-14
[H+]=1.0x10-14/[OH-]=1.0x10-14/0.010
1.0x10-12 M
basic because [OH-]>[H+]
What are the 7 strong acids?
HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4
Bronsted-Lowry acid: substance that donates a proton to another substance
Bronsted-Lowry base: substance that accepts a proton
The hydrogen sulfite ion is amphoteric. Write an equation for the reaction of HSO3- with water in which the ion acts as a base.
In order for HSO3- to act as a base, wit must accept a proton from H2O. This proton transfer will create sulfurous acid and hydroxide ions.
HSO3- (aq) + H2O (l) <--> H2SO3 (aq) + OH- (aq)
What is the ion-product constant for water?
Kw = [H3O+][OH-] = 1.0x10-14 (at 25 degrees Celsius)
Calculate the concentration of H+ (aq) in a solution in which [OH-] os 1.8 x 10-9 M.
[H+]=1.0x10-14/[OH-]=1.0x10-14/1.8x10-9
= 5.6x10-6 M
acidic because [H+] > [OH-]
The larger the value of Ka, the ____ the acid.
stronger
Describe a Lewis acid and a Lewis base.
Lewis acid: electron pair acceptor
Lewis base: electron pair donor
When lithium oxide is dissolved in water, the solution turns basic from the reaction of the oxide ion with water. Write the balanced chemical equation for this reaction.
O2- (aq) + H2O (l) <--> 2OH- (aq)
What is the equation to calculate pH? What is the equation to calculate pOH?
pH = -log[H+]
pOH = -log[OH-]
A sample of freshly pressed apple juice has a pOH of 10.24. Calculate [H+].
pH = 14.00-pOH
pH=14.00-10.24=3.76
pH=-log[H+]=3.76
10log[H+] = 10-3.76
[H+] = 1.7x10-4 M
The more stable the conjugate base the ____ the acid.
stronger
Describe when an amphoteric substance acts as an acid compared to when it acts as a base.
An amphoteric substance acts as a base when combined with something more strongly acidic than itself.
An amphoteric substance acts as an acid when combined with something more strong basic than itself.
If we represent a general weak acid as HA, we can write the equation for its ionization in two ways depending on whether the hydrated proton is represented as H3O+ (aq) or H+ (aq). What are the two ways to write the equation?
HA (aq) + H2O (l) <--> H3O+ (aq) + A- (aq)
OR
HA (aq) <--> H+ (aq) + A- (aq)
percent ionization =
percent ionization = (concentration of ionized HA/original concentration of HA) x 100%
This is the 5% rule! %I=%D (dissociated)
A solution formed by dissolving an antacid tablet has a POH of 4.82. What is [H+] in this solution?
pH+pOH= 14.00
pH=14.00-pOH
pH=14.00-4.82=9.18
pH=-log[H+]
9.18=-log[H+]
10-9.18=10log[H+]
[H+]=6.6x10-10 M
What is the common-ion effect?
Whenever a weak electrolyte and a strong electrolyte containing a common ion are together in solution, the weak electrolyte ionizes less than it would if it were alone in solution.
Describe a strong acid and describe a weak acid along with their conjugate bases.
Strong acid: completely transwers its protons to waterso no undissociated molecules are in solution. A conjugate base of a strong acid shows negligible basicity.
Weak acid: only partly dissociates in aqueous solution and exists in solution as a mixture of undissociated acid and its conjugate base. A conjugate base of a weak acid is a weak base.
What is the general form equation for a weak base? Write the equilibrium constant expression for the weak base.
B (aq) + H2O (l) <--> HB+ (aq) + OH- (aq)
Kb = [BH+][OH-]/[B]
Write the equation that shows the relationship between Ka and Kb. When Ka>Kb, then it's ___. When Kb>Ka, it's ___.
Ka x Kb = Kw
Ka>Kb, acidic
Kb>Ka, basic
The concentration of OH- in an aqueous solution is 8.0x10-5 M at room temperature. What is the pH of this solution?
pOH=-log[OH-]
pOH=-log[8.0x10-5]=4.1
pH+pOH=14.00
pH=14.00-pOH
pH=14.00-4.1=9.90
For a general ionic solid, AnXm, what does the solubility-product constant equal?
Ksp = [A+]n[X-]m