Question 39 of 69intermediate🔧 ApplyShort Answer2 marks

The species: H2O,HCO3−,HSO4−H_2O, HCO_3^-, HSO_4^- and NH3NH_3 can act both as Brönsted acids and bases. For each case give the corresponding conjugate acid and base.

Correct Answer

According to the Brönsted-Lowry theory, a conjugate acid is formed when a species accepts a proton (H+H^+), and a conjugate base is formed when a species donates a proton. The species H2O,HCO3−,HSO4−H_2O, HCO_3^-, HSO_4^- and NH3NH_3 can act both as Brönsted acids and bases.

For each species, the corresponding conjugate acid and base are:

  • For H2OH_2O: Conjugate acid is H3O+H_3O^+ and conjugate base is OH−OH^-.
  • For HCO3−HCO_3^-: Conjugate acid is H2CO3H_2CO_3 and conjugate base is CO32−CO_3^{2-}.
  • For HSO4−HSO_4^-: Conjugate acid is H2SO4H_2SO_4 and conjugate base is SO42−SO_4^{2-}.
  • For NH3NH_3: Conjugate acid is NH4+NH_4^+ and conjugate base is NH2−NH_2^-.
Exercise: EXERCISES | Q: 6.39 | (Page 45)
For More Understanding

Explanation

The question tests the understanding of amphoteric species in the Brönsted-Lowry acid-base theory. A conjugate acid has one extra proton compared to the base, and a conjugate base has one less proton compared to the acid. The textbook provides a direct table mapping these species to their conjugate acids and bases.

Solution Steps

  1. Step 1: Identify that a conjugate acid is formed by gaining a proton (H+H^+) and a conjugate base is formed by losing a proton.

  2. Step 2: Apply this rule to H2OH_2O to get H3O+H_3O^+ (acid) and OH−OH^- (base).

  3. Step 3: Apply this rule to HCO3−HCO_3^- to get H2CO3H_2CO_3 (acid) and CO32−CO_3^{2-} (base).

  4. Step 4: Apply this rule to HSO4−HSO_4^- to get H2SO4H_2SO_4 (acid) and SO42−SO_4^{2-} (base).

  5. Step 5: Apply this rule to NH3NH_3 to get NH4+NH_4^+ (acid) and NH2−NH_2^- (base).

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