Acid Base Equilibrium
How are ka, kb, and kw all related to one another?
(ka)(kb)= kw; kw= 1x10^-14
What is the pH of an aqueous solution at 25.0 °C in which [OH-] is 0.00250M?
+11.4
The Ka of hypochlorous acid (HClO) is 3.00 × 10^-8 What is the pH at 25.0 °C of an aqueous solution that is 0.0200 M in HClO?
+4.61
In which of the following aqueous solutions does the weak acid exhibit the highest percentage ionization?
0.01 M HF (Ka = 6.8 x 10^-4)
The Ka of hypochlorous acid (HClO) is 3.0 × 10^-8 at 25.0°C. What is the % ionization of hypochlorous acid in a 0.015-M aqueous solution of HClO at 25.0°C?
0.14
The acid-dissociation constants of phosphoric acid (H3PO4) are Ka1 = 7.5 x 10^-3, Ka2 = 6.2 x 10^-8, and Ka3 = 4.2 x 10^-13 at 25.0 °C. What is the pH of a 2.5 M aqueous solution of phosphoric acid?
0.87
The molar concentration of hydronium ion in pure water at 25°C is __________.
1.0 x 10^-7
The molar concentration of hydroxide ion in pure water at 25°C is __________.
1.0 x 10^-7
An aqueous solution at 25.0 °C contains [H+] = 0.0990 M. What is the pH of the solution?
1.00
The acid-dissociation constants of sulfurous acid (H2SO3) Ka1 = 1.7 x 10^-2 and Ka2= 6.4 x 10^-8 at 25.0 °C. Calculate the pH of a 0.163 M aqueous solution of sulfurous acid.
1.4
A 0.15 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 5.35. The value of Ka for HA is __________.
1.4 x 10^-10
Ka for HF is 7.0 × 10^-4. Kb for the fluoride ion is __________.
1.4 x 10^-11
What is the pOH of a 0.0150 M solution of barium hydroxide?
1.52
Calculate the concentration (in M) of hydronium ions in a solution at 25.0 °C with a pOH of 4.223.
1.67 x 10^-10
The Ka of hydrofluoric acid (HF) at 25.0 °C is 6.8 × 10^-4. What is the pH of a 0.35 M aqueous solution of HF?
1.8
What is the concentration (in M) of hydroxide ions in a solution at 25.0 °C with pH = 4.282?
1.92 x 10^-10
Ka for HCN is 4.9 × 10^-10. What is the pH of a 0.068 M aqueous solution of sodium cyanide?
11
Calculate the pH of a 0.500 M aqueous solution of NH3. The Kb of NH3 is 1.77 x 10^-5.
11.5
Determine the pH of a 0.35 M aqueous solution of CH3NH2 (methylamine). The Kb of methylamine is 4.4 x 10^-4.
12
Ka for HX is 7.5 × 10^-12. What is the pH of a 0.15 M aqueous solution of NaX?
12
What is the pH of a 0.0150 M aqueous solution of barium hydroxide?
12.5
An aqueous solution contains 0.100 M NaOH at 25.0 °C. The pH of the solution is __________.
13.0
The acid-dissociation constants of phosphoric acid (H3PO4) are Ka1 = 7.5 x 10^-3, Ka2 = 6.2 x 10^-8, and Ka3 = 4.2 x 10^-13 at 25.0°C What is the molar concentration of phosphate ion in a 2.5 M aqueous solution of phosphoric acid?
2.0 x 10^-19
The Ka for HCN is 4.9 × 10^-10. What is the value of Kb for CN-?
2.0 x 10^-5
The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0 °C is 4.48. What is the value of Ka for HBrO?
2.0 x 10^-9
The acid-dissociation constant, Ka, for gallic acid is 4.57 × 10^-3. What is the base-dissociation constant, Kb, for the gallate ion?
2.19 x 10^-12
The pH of an aqueous solution at 25.0 °C is 10.66. What is the molarity of H+ in this solution?
2.2 x 10^-11
The Ka of hydrazoic acid (HN3) is 1.9 × 10^-5 at 25.0 °C. What is the pH of a 0.35 M aqueous solution of HN3?
2.6
What is the pH of an aqueous solution at 25.0 °C in which [H+] is 0.00250M?
2.60
The acid-dissociation constant for chlorous acid, HClO2, at 25.0 °C is 1.0 × 10^-2. Calculate the concentration of H+ if the initial concentration of acid is 0.10 M.
2.7 x 10^-2
Calculate the pOH of a solution at 25.0 °C that contains 1.94 × 10^-10 M hydronium ions.
4.29
The pH of a 0.10 M solution of a weak base is 9.82. What is the Kb for this base?
4.3 x 10^-8
The Ka of hypochlorous acid (HClO) is 3.00 × 10^-8 at 25.0 °C. Calculate the pH of a 0.0385 M hypochlorous acid solution.
4.47
An aqueous solution contains 0.050 M of methylamine. The concentration of hydroxide ion in this solution is ________M. Kb for methylamine is 4.4 x 10^-4.
4.5 x 10^-3
Kb for NH3 is 1.8 × 10^-5. What is the pH of a 0.35 M aqueous solution of NH4Cl at 25.0C?
4.9
Calculate the pOH of a 0.0827 M aqueous sodium cyanide solution at 25.0 °C. Kb for CN- is 4.9 × 10^-10
5.2
What is the concentration (in M) of hydronium ions in a solution at 25.0 °C with pH = 4.282?
5.22 x 10^-5
Calculate the pH of 0.726 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that Kb for aniline is 3.83 x 10^-4
5.36
What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10^-9 M hydronium ion?
5.60
The concentration of water in pure water is approximately __________ M.
55
The pH of a 0.15 M aqueous solution of NaZ (the sodium salt of HZ) is 10.7. What is the Ka for HZ?
6.0 x 10^-9
HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0 °C. The Ka of HZ is ________.
6.9 x 10^-9
The base-dissociation constant, Kb, for pyridine, C5H5N, is 1.4 x 10^-9. The acid-dissociation constant, Ka, for the pyridinium ion, C5H5NH+ is __________.
7.1 x 10^-6
Determine the pH of a 0.15 M aqueous solution of KF. For hydrofluoric acid Ka = 7.0 x 10^-4
8.2
What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10^-9 M hydronium ion?
8.40
The Ka for formic acid (HCO2H) is 1.8 × 10^-4. What is the pH of a 0.35 M aqueous solution of sodium formate (NaHCO2)?
8.6
What is a buffered solution? What purpose do buffered solutions serve in the world of biology? Describe how I would prepare a buffered solution.
A buffered solution is a weak acid and it's related basic salt that resists changes in pH
HA is a weak acid. Which equilibrium corresponds to the equilibrium constant Kb for A-?
A- (aq) + H2O (l) --> HA (aq) + OH- (aq)
Which one of the following is a Brønsted-Lowry acid? A) (CH3)3NH+ B) CH3COOH C) HF D) HNO2 E) all of the above
All of the above
What term/s do we use to describe substances that act as both an acid and a base? Give one example.
Amphoteric—> water
How does the Arrhenius definition of acids and bases differ from the Brønsted-Lowery definition? Give examples of both.
Arrhenius is not all encompassing whereas the Brønsted-Lowery is. Arrhenius—> Acids increases hydronium ions; bases increase hydroxide ions Brønsted-Lowery—> Acids proton donor + must have a removable acidic proton; bases proton acceptor + must have a pair of non-bonding electrons on central atom.
Which of the following ions will act as a weak base in water?
ClO-
Describe how certain salts react with H2O to form basic solutions and how other salts react with H2O to form acidic solutions. Give one example of each and illustrate how it reacts with H2O to form a basic or acidic solution.
During hydrolysis, one of the ions form a salt reacts with H2O forming either a basic or an acidic solution. A strong acid and a weak base form an acidic salt solution. A weak acid and a string base from a basic salt solution.
The conjugate acid of HSO4- is
H2SO4
Which one of the following is the weakest acid?
HCN (Ka= 4.9 x 10^-10)
What are the seven strong acids?
HCl, HBr, HI, HNO3, H2SO4, HClO3, HClO4
Of the following, __________ is a weak acid.
HF
Of the following acids, __________ is not a strong acid.
HNO2
Nitric acid is a strong acid. This means that ____________.
HNO3 dissociates completely to H+ (aq) and NO3- (aq) when it dissolves in water
Of the compounds below, a 0.1 M aqueous solution of __________ will have the highest pH.
KCN , Ka of HCN = 4.0 x 10-10
A 0.1 M aqueous solution of __________ will have a pH of 7.0 at 25.0 °C. NaOCl , KCl , NH4Cl , Ca(OAc)2
KCl
What are the eight strong bases?
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
What is the conjugate acid of NH3?
NH4+ (it's acting as a base so it accepts a proton)
An aqueous solution of __________ will produce a basic solution.
Na2SO3
Of the following substances, an aqueous solution of __________ will form basic solutions. NH4Cl Cu(NO32) K2CO3 NaF
NaF, K2CO3
A 0.1 M solution of _______ has a pH of 7.0.
NaNO3
What is the conjugate base of OH-?
O2-
The hydride ion, H- , is a stronger base than the hydroxide ion, OH- hydride ion with water is/ are __________.
OH- (aq) + H2 (g)
The conjugate base of HSO4- is
SO4^-2
What is the difference between strong and weak acids?
Strong acids fully dissociate whilst weak acids do not.
What does the ka value for a compound tell us about that compound?
The ka value for a compound is the acid dissociation constant. The ka value tells us how much the acid will dissociate in an aqueous solution. The larger the ka value, the stronger the acid.
What does the kb value for compound tell us about that compound?
The kb value is the base dissociation constant for a compound. It tells us how much the base dissociated in an aqueous solution.
Which one of the following statements regarding Kw is false?
The value of Kw is always 1.0 x 10^-14
Classify the following compounds as weak acids (W) or strong acids (S): hypochlorous acid, perchloric acid, chloric acid
W S S
Classify the following compounds as weak acids (W) or strong acids (S): nitrous acid, hydrochloric acid, hydrofluoric acid
W S W
Classify the following compounds as weak bases (W) or strong bases (S): ammonia, flouride ion, sodium hydroxide
W, W, S,
Describe what an acid base conjugate pair is and give at least one example
What each turns into whether they act as an acid or base; H2X+ <—Hx—> X-
In basic solution, __________.
[H3O+] < [OH-]
A Brønsted-Lowry base is defined as a substance that __________.
acts as a proton acceptor
A Brønsted-Lowry acid is defined as a substance that __________.
acts as a proton donor
A substance that is capable of acting as both an acid and as a base is __________.
amphoteric
An aqueous solution contains 0.10 M NaOH. The solution is __________.
basic
According to the Arrhenius concept, an acid is a substance that __________.
causes an increase in the concentration of H+ in aqueous solutions
When a lowercase "p" is placed in front of ka,kb,kw, [H+] or [OH-], what does it mean mathematically?
p= partiae -log ()
Which solution below has the highest concentration of hydroxide ions?
pH = 12.49
Which of the following aqueous solutions has the highest [OH-]
pure water
A 0.0035-M aqueous solution of a particular compound has pH = 2.46. The compound is __________.
strong acid
The magnitude of Kw indicates that __________.
water autoionizes only to a very small extent
Ammonia is a __________.
weak base
