Deck 7: Acids and Bases

Question 1

Identify the type of species highlighted in red in the following equation:
NH₃ (aq) + HF (aq) ⇌ NH₄⁺ (aq) + F^- (aq)
Please select all that apply.

A) Arrhenius base
B) Brønsted-Lowry acid
C) Arrhenius acid
D) Brønsted-Lowry base

Answer 1

D

Question 2

In water the H⁺ ion is always hydrated and found as the H₃O⁺ ion.

Answer 2

True

Question 3

The conjugate acid of H₂PO₄^- is H₃PO₄.

Answer 3

True

Question 4

Water can be described as amphoteric as it can be both a proton donor and a proton acceptor.

Question 5

Choose which expression for the equilibrium constant for the reaction of water with perchloric (HClO₄) acid is correct.

A)
B)
C)
D)

Question 6

HClO₄ is a strong acid, therefore ClO₄^- must be a _____ base

Question 7

What is the hydrogen ion concentration of a can of cola with pH = 2.77?

A) 588 mol dm^-3
B) 2.34 x 10^-3 mol dm^-3
C) 0.56 x 10^-3 mol dm^-3
D) 1.70 x 10^-3 mol dm^-3

Question 8

The pH of a 0.345 mol dm^-3 solution of nitric acid is 0.46.

Question 9

HF has the ability to dissolve glass, it is a _____ acid.

Question 10

Which of the following statements apply to a weak acid?

A) In the equilibrium equation:
HA (aq) + H₂O (l) ⇌ A^- (aq) + H₃O⁺ (aq)
The equilibrium lies almost entirely to the right.
B) pK_a is less than 0.
C) The pH would be greater than zero.
D) The pH would be less than zero.

Question 11

Sn²⁺ is rapidly oxidised to Sn⁴⁺ in solution. Hydrolysis of Sn⁴⁺ ions causes the pH of the solution to rise.

Question 12

The pH of a 0.111 mol dm^-3 HCO₂H solution at 298 K is 0.95.

Question 13

Many solvents self ionize to form an anion and cation that are the Brønsted- Lowry base and acid of the original solvent. Match the ions with the solvent from which they are generated.
-H₃PO₄

A) H₂PO₄^-
B) NH₂^-
C) H₃SO₃⁺
D) H₃O⁺

Question 14

Many solvents self ionize to form an anion and cation that are the Brønsted- Lowry base and acid of the original solvent. Match the ions with the solvent from which they are generated.
-NH₃

A) H₂PO₄^-
B) NH₂^-
C) H₃SO₃⁺
D) H₃O⁺

Question 15

Many solvents self ionize to form an anion and cation that are the Brønsted- Lowry base and acid of the original solvent. Match the ions with the solvent from which they are generated.
-H₂SO₃

A) H₂PO₄^-
B) NH₂^-
C) H₃SO₃⁺
D) H₃O⁺

Question 16

Many solvents self ionize to form an anion and cation that are the Brønsted- Lowry base and acid of the original solvent. Match the ions with the solvent from which they are generated.
-H₂O

A) H₂PO₄^-
B) NH₂^-
C) H₃SO₃⁺
D) H₃O⁺

Question 17

K_w falls with temperature as the self-ionization of water is exothermic.

Question 18

The position of neutral pH on the pH scale changes with temperature.

Question 19

Which of the following statements are true when referring to a buffer solution? Please select all that apply.

A) A buffer can consist of a weak acid and its salt.
B) A buffer solution is resistant to addition of small quantities of acid.
C) A buffer can consist of a weak base and its salt.
D) A buffer solution is resistant to addition of small quantities of base.

Question 20

A buffer can be made from a weak base and the ____ of that base.

Question 21

What is the pH of a buffer solution containing 0.155 mol dm^-3 of benzoic acid and 0.315 mol dm^-3 sodium benzoate. (K_a of benzoic acid is 4.20.)

A) 0.50
B) -0.50
C) 3.89
D) 4.51

Question 22

Which of the following indicators would be suitable for the titration of HCO₂H with sodium hydroxide?

A) Phenolphthalein
B) Methyl orange
C) Bromocresol blue
D) Thymol blue

Question 23

The strength of an oxoacid, H_mXO_n containing m hydroxide groups and (n - m) double bonded oxygen atoms is related to?

A) n
B) n - m
C) n + m
D) m

Question 24

A polybasic acid is an acid with more than one ionisable ________ atom.

Question 25

CaO is described as being a basic oxide because it forms an alkaline solution with water.

Question 26

Which of the following species could be described as Lewis acids? Please select all that apply.

A) Co³⁺
B) F^-
C) BCl₃
D) I₂

Question 27

NH₃ is a Brønsted-Lowry base and a Lewis base.