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WorksheetsAcid-Base Equilibria
Total questions: 40
Worksheet time: 1hrs 2mins
Why is indicator added to a titration?
To test for acids
to show the endpoint
to prove a reaction has happened
to show a colour
Which of the following salts forms an aqueous solution with the lowest pH value?
NH4NO3
Ca(NO3)2
KNO3
Mg(NO3)2
The following solutions are buffer solutions EXCEPT
NH3 and NH4Cl
HC2H3O2 and NH4C2H3O2
HC2H3O2 and NaC2H3O2
NH3 and (NH4)2SO4
Which of the following cations does NOT form an acidic solution?
Na+
NH4+
Al3+
Fe3+
Which is a stronger acid and why? NH3 and PH3
NH3 because N is more electronegative, creating a more polar bond.
PH3 because in binary acids the strength (length) of the bond is weaker
Predict which compound in each of the following pairs of compounds is more acidic and explain your reasoning for each. Note: the H is attached to an oxygen.
HSO4- because the S is more electronegative
HSeO4- because Se has a weaker bond
Which relationship relates Ka, Kb and Kw?
Kw = Ka + Kb
Kw = Kb/Ka
Ka = Kw + Kb
Kb = Kw/Ka
Which salt will form an acidic solution?
NH4Cl
NaCl
NaHCO3
BaCl2
Which acid produces the strongest conjugate base?
HClO4 (Ka= 1.0 x 107)
HCN (Ka= 4.0 x 10-10)
H3PO4 (Ka= 7.5 x 10-3)
H2CO3 (Ka = 4.2 x 10-7)
Which two species are acting as Bronsted-Lowry bases in the reaction shown below?
HF(aq) + NH3(aq) ⇌ F-(aq) + NH4+(aq)
HF and F-
NH3 and F-
NH3 and NH4+
NH4+ and F-
An Arrhenius acid
donates an H+
increases the concentration of H+
accepts a pair of electrons
reacts with the solvent to form a cation
The Ka for HF is 7.0 x 10-4. What is the Kb for F-?
1.4 x 10-11
2.0 x 10-8
7.0 x 10-18
7.0 x 10-4
1.4 x 103
Calculate the pH of a 0.500 M NH3 solution. The Kb of ammonia is 1.77x 10-5.
12.58
2.98
11.47
10.69
What is the conjugate acid of NH3?
NH4+
NH2-
NH4OH
NH4
What is the conjugate base of HSO4-
H2SO4
SO42-
H2SO4+
HSO42-
Which solution below has the highest concentration of hydroxide ions?
pH = 3.21
pH = 9.82
pH = 7.93
pH = 12.59
What is the pH of a 0.015-M aqueous solution of barium hydroxide?
12.48
1.52
12.18
1.82
Of the following, __________ is a weak base.
CH₃NH₂
HCl
HNO₂
KOH
Which one of the following is the weakest acid?
HF (Ka = 6.8 x 10⁻⁴)
HC₂H₃O₂ (Ka = 1.8 x 10⁻⁵)
HNO₂ (Ka = 4.5 x 10⁻⁴)
HClO (Ka = 3.0 x 10⁻⁸)
The Ka of hypochlorous acid (HClO) is 3.0 x 10⁻⁸. What is the pH at 25°C of an aqueous solution that is 0.020 M in HClO?
7.00
2.45
4.61
9.22
Kw = [H₃O⁺] [OH⁻] = 1.0 x 10⁻¹⁴ at 25°C Based on this information, which of the following is true for a sample of pure water at 25°C?
[H₃O⁺] = 7.0 M
[OH⁻] = 1.0 x 10⁻¹⁴ M
pH = 10⁻⁷
pOH = 7.00
Which acid below has the WEAKEST conjugate base?
Hydrofluoric acid, HF
(Ka = 7.2 x 10⁻⁴)
Acetic Acid, CH₃COOH
(Ka = 1.8 x 10⁻⁵)
Hydrocyanic acid, HCN
(Ka = 6.2 x 10⁻¹⁰)
Formic acid, HCOOH
(Ka = 1.8 x 10 ⁻⁴)
Mixtures that would be considered buffers include which of the following?
0.10 M HCl + 0.10 M NaCl
0.10 M HF + 0.10 M NaF
0.10 M HBr + 0.10 M NaBr
0.10 M HI + 0.10 M NaI
A buffer solution is prepared by mixing equal volumes of 0.50 M weak acid with 1.0 M of its conjugate base. Based on the data given in the table above, which of the following pairs of chemical solutions should be used to prepare the buffer solution so that the pH will be between 4 and 7?
CH3COOH and NH3
CH3COOH and CH3COONa
H2CO3 and NH3
H2CO3 and Na2CO3
Which of the following acids along with their conjugate base, would make the most effective buffer to maintain the pH of a solution at 4.95?
acetic acid (Ka = 1.8 x 10-5)
benzoic acid (Ka = 6.4 x 10-5)
hydrofluoric acid (Ka = 7.2 x 10-4)
lactic acid (Ka = 1.4 x 10-4)
Hydrochloric acid (HCl) and acetic acid (HC2H3O2) are both acids. HCl completely dissociates in water, while HC2H3O2 does not. Which of the following statements best describes these two acids?
HCl is a weak acid, HC2H3O2 is a weak acid.
HCl is a strong acid, HC2H3O2 is a strong acid.
HCl is a strong acid, HC2H3O2 is a weak acid.
HCl is a weak acid, HC2H3O2 is a strong acid.
What is the conjugate acid of CO3-2?
CO2-2
HCO22-2
H2CO3
HCO3-1
What is the pH of a 0.053 M solution of potassium hydroxide
6.91
12.72
7.33
1.28
Which chemical is a proton acceptor?
Acid
Base
Which of the following gives the best estimate for the pH of a 1 × 10⁻⁵ M HClO₄ (aq) solution at 25°C?
pH = 1.0, because HClO₄ is a strong acid
pH = 5.0, because HClO₄ is a strong acid
pH = 7.0, because HClO₄ is a strong base
pH = 9.0, because HClO₄ is a strong base
Which species in the equation below are behaving as Bronsted-Lowry ACIDS?
NH3 + H2O ⇌ NH4+ + OH-
NH₃ and H₂O
H₂O and NH₄⁺
NH₃ and OH⁻
NH₄⁺ and OH⁻
Which of the following would be the SAME for equal volumes of 1.0 M HCl and
1.0 M HF?
pH
percent ionization
conductivity
moles of NaOH needed to neutralize acid sample
A solution contains 0.04 M of a weak acid. Calculate the pH of the solution knowing that the Ka for the acid is 1.6 x 10-7
It is not possible to solve if the identity of the acid is not known
4.1
4.9
Because the Ka is very small, the pH is close to neutral (about 6)
