Question

Which of the chemical equations below are acid-base (proton transfer) reactions? select all that apply. mg(oh)2 (s) + h2so4 (aq) → mgso4 (s) + 2 h2o (l) fe(no3)3 (aq) + 3 koh (aq) → fe(oh)3 (s) + 3 kno3 (aq) zn (s) + cu(no3)2 (aq) → zn(no3)2 (aq) + cu (s) mg (s) + cu(no3)2 (aq) --> mg(no3)3 (aq) + cu (s) hcl (aq) + koh (aq) → kcl (aq) + h2o (l) nh3 (aq) + hcl (aq) → nh4cl (aq)?

Answer 1

• Mg(OH)₂ (s) + H₂SO₄ → MgSO₄ (s) + 2 H₂O (l).
• HCl (aq) + KOH (l) → KCl (aq) + H₂O (l).
• NH₃ (aq) + HCl (aq) → NH₄Cl (aq).

Step-by-step explanation

There are three acid-base theories: Arrhenius, Bronsted-Lowry, and Lewis. Among the three, only the Bronsted-Lowry theory defines acids and bases based on the transfer of protons H⁺.

• A Bronsted-Lowry acid is a proton donor;
• A Bronsted-Lowry base is a proton acceptor.

Mg(OH)₂ (s) + H₂SO₄ → MgSO₄ (s) + 2 H₂O (l)

• Mg(OH)₂ acts as a base and accepts protons H⁺.
• H₂SO₄ acts as an acid and loses protons H⁺.

Fe(NO₃)₃ (aq) + 3 KOH (aq) → Fe(OH)₃ (s) + 3 KNO₃ (aq)

• There's a transfer of OH⁻ and NO₃⁻ but not protons H⁺.

Zn (s) + Cu(NO₃)₂ (aq) → Zn(NO₃)₂ (aq) + Cu(s)

• Zn loses electrons to Cu²⁺ in Cu(NO₃)₂.
• There's no transfer of protons H⁺.

Mg (s) + Cu(NO₃)₂ (aq) → Mg(NO₃)₂ + Cu (s)

• Mg loses electrons to Cu²⁺ in Cu(NO₃)₂.
• There's no transfer of protons H⁺.

HCl (aq) + KOH (aq) → KCl (aq) + H₂O (l)

• HCl acts as an acid and loses protons H⁺.
• KOH acts as a base and gains protons H⁺.

NH₃ (aq) + HCl (aq) → NH₄Cl (aq)

`\text{HCl} \to \text{H}^(+)\;(aq) + \text{Cl}^(-)\;(aq)\\\begin{array}{ll}\text{Ionic equation} & \text{NH}_3 \;(aq)+ \text{H}^(+)\;(aq) +\text{Cl}^(-)\;(aq)\to {\text{NH}_4}^(+) \;(aq)+\text{Cl}^(-)\;(aq)\\\text{Net Ionic equation} & \text{NH}_3 \;(aq)+ \text{H}^(+)\;(aq) \to {\text{NH}_4}^(+) \;(aq)\end{array}`

• HCl acts as an acid and loses protons H⁺.
• NH₃ acts as a base and gains protons H⁺.