DP Chemistry Questionbank

Which species acts as a Lewis and Brønsted–Lowry base?

A.      [Al(H₂O)₆]³⁺

B.      BF₃

C.      NH₄⁺

D.      OH⁻

Calculate the amount, in mol, of NaOH(aq) used.

Identify one conjugate acid-base pair in the reaction.

Identify the amphiprotic species.

Which of these acids has the weakest conjugate base?

A.  $\mathrm{HCl}$

B.  ${\mathrm{CH}}_3\mathrm{COOH}$

C.  ${\mathrm{NH}}_4\mathrm{Cl}$

D.  ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}$

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

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

State the formula of the conjugate base of hypochlorous acid.

State the formula of the conjugate base of hypochlorous acid.

Calculate the $K_{\mathrm{b}}$ of the conjugate base of ethanoic acid using sections 2 and 21 of the data booklet.

A student working in the laboratory classified HNO₃, H₂SO₄, H₃PO₄ and HClO₄ as acids based on their pH. He hypothesized that “all acids contain oxygen and hydrogen”.

Evaluate his hypothesis.

Which is a Lewis acid, but not a Brønsted-Lowry acid?

A.  ${\text{BF}}_3$

B.  ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$

C.  ${\text{NH}}_3$

D.  ${\text{Cl}}^{-}$

Write an equation to show ammonia, NH₃, acting as a Brønsted–Lowry base and a different equation to show it acting as a Lewis base.

Which classification is correct for the reaction?

H₂PO₄⁻(aq) + H₂O(l) → HPO₄²⁻(aq) + H₃O⁺(aq)

Outline why H₃PO₄/HPO₄²⁻ is not a conjugate acid-base pair.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Formulate two equations to show the amphiprotic nature of H₂PO₄⁻.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Formulate two equations to show the amphiprotic nature of H₂PO₄⁻.

State the equation for the reaction of each substance with water.

Which two species act as Brønsted–Lowry acids in the reaction?

H₂PO₄⁻ (aq) + OH⁻ (aq) $\rightleftharpoons$ HPO₄²⁻ (aq) + H₂O (l)

A. HPO₄²⁻ (aq) and OH⁻ (aq)

B. H₂PO₄⁻ (aq) and HPO₄²⁻ (aq)

C. HPO₄²⁻ (aq) and H₂O (l)

D. H₂PO₄⁻ (aq) and H₂O (l)

State the equation for the reaction of each substance with water.

Draw the structure of the conjugate base of benzoic acid showing all the atoms and all the bonds.

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Draw the structure of the conjugate base of benzoic acid showing all the atoms and all the bonds.

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.