Which type of bond is formed when a Lewis acid reacts with a Lewis base?

A.     Covalent

B.     Dipole-dipole

C.     Double

D.     Hydrogen

Which salt solution has the highest pH?

A. NH₄Cl

B. Ca(NO₃)₂

C. Na₂CO₃

D. K₂SO₄

Which mixture is a buffer solution?

A.  25 cm³ of 0.10 mol dm^-3 NH₃ (aq) and 50 cm³ of 0.10 mol dm^-3 HCl (aq)

B.  50 cm³ of 0.10 mol dm^-3 NH₃ (aq) and 25 cm³ of 0.10 mol dm^-3 HCl (aq)

C.  25 cm³ of 0.10 mol dm^-3 NaOH (aq) and 25 cm³ of 0.10 mol dm^-3 HCl (aq)

D.  50 cm³ of 0.10 mol dm^-3 NaOH (aq) and 25 cm³ of 0.10 mol dm^-3 HCl (aq)

A buffer is produced by mixing 20.0 cm³ of 0.10 mol dm⁻³ ethanoic acid, CH₃COOH(aq), with 0.10 mol dm⁻³ sodium hydroxide, NaOH(aq).

What is the volume of NaOH required and the pH of the buffer?

Which combination will produce an alkaline buffer in water?

A.  0.10 mol NH₃ and 0.05 mol H₂SO₄

B.  0.50 mol NH₃ and 0.10 mol H₂SO₄

C.  0.10 mol CH₃COOH and 0.05 mol NaOH

D.  0.10 mol CH₃COOH and 0.50 mol NaOH

Which statements are correct?

        I. Lewis bases can act as nucleophiles.

        II. Electrophiles are Lewis acids.

        III. Lewis acids are electron pair acceptors.

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Which compound is acidic in aqueous solution?

A.  KBr

B.  CH₃COONa

C.  NH₄Cl

D.  Na₂CO₃

An indicator, HIn, has a pK_a of 5.1.

HIn (aq) $\rightleftharpoons$ H⁺ (aq) + In⁻ (aq)

colour A                      colour B

Which statement is correct?

A.   At pH = 7, colour B would be observed
B.   At pH = 3, colour B would be observed
C.   At pH = 7, [HIn] = [In⁻]
D.   At pH = 3, [HIn] < [In⁻]

Which species are both Lewis and Brønsted–Lowry bases?

I.   CN⁻
II.  OH⁻
III. NH₃

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Which is a Lewis acid but not a Brønsted−Lowry acid?

A. AlCl₃

B. CH₃CO₂H

C. HF

D. CCl₄

What is the order of increasing pH for the following solutions of the same concentration?

A.   NaCl < NH₄Cl < Na₂CO₃ < CH₃COONa

B.   CH₃COONa < NH₄Cl < NaCl < Na₂CO₃

C.   NH₄Cl < NaCl < CH₃COONa < Na₂CO₃

D.   Na₂CO₃ < CH₃COONa < NaCl < NH₄Cl

The following equation represents the dissociation of water at 25 °C.

2H₂O (l) $\rightleftharpoons$ H₃O⁺ (aq) + OH⁻ (aq)        ΔH = +56 kJ

Which changes occur as the temperature increases?

A. [H₃O⁺] increases and pH will decrease.

B. [H₃O⁺] decreases and pH will increase.

C. [H₃O⁺] increases and pH will increase.

D. [H₃O⁺] decreases and pH will decrease.

What is the order of increasing acidity?

A.     HClO < CH₃CH₂COOH < HF < HIO₃

B.     HClO < HF < CH₃CH₂COOH < HIO₃

C.     HIO₃ < HF < CH₃CH₂COOH < HClO

D.     HIO₃ < CH₃CH₂COOH < HF < HClO

What is the order of increasing acidity of the following acids?

A.     chloroethanoic < ethanoic < hydrogen fluoride < hydrogen cyanide

B.     ethanoic < chloroethanoic < hydrogen fluoride < hydrogen cyanide

C.     chloroethanoic < ethanoic < hydrogen cyanide < hydrogen fluoride

D.     hydrogen cyanide < ethanoic < hydrogen fluoride < chloroethanoic

In which set are the salts arranged in order of increasing pH?

A.  HCOONH₄ < KBr < NH₄Br < HCOOK

B.  KBr < NH₄Br < HCOOK < HCOONH₄

C.  NH₄Br < HCOONH₄ < KBr < HCOOK

D.  HCOOK < KBr < HCOONH₄ < NH₄Br

Which is an example of a Lewis base?

A.     an electrophile

B.     BF₃

C.     CH₄

D.     a nucleophile

Which of the following will form a buffer solution if combined in appropriate molar ratios?

A. HCl and NaCl

B. NaOH and HCOONa

C. NH₄Cl and HCl

D. HCl and NH₃

Which species is not a Lewis base?

A.   OH⁻

B.   NH₄⁺

C.   H₂O

D.   PH₃

Which indicator is appropriate for the acid-base titration shown below?

A. Thymol blue (pK_a = 1.5)
B. Methyl orange (pK_a = 3.7)
C. Bromophenol blue (pK_a = 4.2)
D. Phenolphthalein (pK_a = 9.6)

Which can act as a Lewis acid but not a Brønsted–Lowry acid?

A. BF₃

B. H₂O

C. NF₃

D. NH₃

Which combination of acid and base is most likely to have a pH of 8.5 at the equivalence point in a titration?

A.     Hydrochloric acid and sodium hydroxide

B.     Hydrochloric acid and ammonia

C.     Nitric acid and ammonia

D.     Methanoic acid and sodium hydroxide

Which has the strongest conjugate base?

A. HCOOH (K_a = 1.8 × 10⁻⁴)

B. HNO₂ (K_a = 7.2 × 10⁻⁴)

C. HCN (K_a = 6.2 × 10⁻¹⁰)

D. HIO₃ (K_a = 1.7 × 10⁻¹)

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

Which statement explains the Lewis acid–base nature of the chloride ion in this reaction?

C₂H₅⁺ + Cl^– → C₂H₅Cl

A.  Lewis base because it donates a pair of electrons

B.  Lewis base because it accepts a pair of electrons

C.  Lewis acid because it donates a pair of electrons

D.  Lewis acid because it accepts a pair of electrons

 Which is correct?

A.  Electrophiles are Brønsted–Lowry acids.

B.  Nucleophiles are Brønsted–Lowry acids.

C.  Electrophiles are Lewis acids.

D.  Nucleophiles are Lewis acids.

What is the order, in increasing pH, of the following solutions of equal concentration?

A. H₃BO₃ < CH₃CH₂CH₂COOH < CH₃CH₂COOH < CHCl₂COOH

B. H₃BO₃ < CH₃CH₂CH₂COOH < CHCl₂COOH < CH₃CH₂COOH

C. CH₃CH₂CH₂COOH < CH₃CH₂COOH < CHCl₂COOH < H₃BO₃

D. CHCl₂COOH < CH₃CH₂CH₂COOH < CH₃CH₂COOH < H₃BO₃

Where is the buffer region for the titration of a weak acid with a strong base?

A weak base is titrated with a strong acid. Which value of pK_b can be estimated from this titration curve?

A.  11.3

B.  9.2

C.  4.8

D.  1.8