IB MYP 4-5 Chemistry -Acid + base, metal, or carbonate reactions- Study Notes - New Syllabus

 Reactions of Acids with Bases, Metals, and Carbonates

Acids react with different classes of substances — bases, metals, and carbonates — in characteristic ways. These reactions help identify acids and are used widely in laboratory and industrial chemistry.

Reaction of Acid with Base — Neutralization

General Equation:

\( \mathrm{Acid + Base \rightarrow Salt + Water} \)

Ionic Equation:

\( \mathrm{H^+(aq) + OH^-(aq) \rightarrow H_2O(l)} \)

Explanation:

• Acids provide hydrogen ions \( \mathrm{(H^+)} \), bases provide hydroxide ions \( \mathrm{(OH^-)} \).
• These ions combine to form water, while the remaining ions form a salt.

Example: \( \mathrm{HCl + NaOH \rightarrow NaCl + H_2O} \)

Reaction of Acid with Metal

General Equation:

\( \mathrm{Acid + Metal \rightarrow Salt + Hydrogen\ gas} \)

Explanation:

• Metals above hydrogen in the reactivity series react with acids.
• Hydrogen gas is released during the reaction.
• Salt formed depends on the acid and the metal used.

Examples:

• \( \mathrm{Mg + 2HCl \rightarrow MgCl_2 + H_2} \)
• \( \mathrm{Zn + H_2SO_4 \rightarrow ZnSO_4 + H_2} \)

Observation: Effervescence (bubbling) occurs due to hydrogen gas production.

Reaction of Acid with Carbonate (or Hydrogen Carbonate)

General Equation:

\( \mathrm{Acid + Carbonate \rightarrow Salt + Water + Carbon\ dioxide} \)

or

\( \mathrm{Acid + Hydrogen\ carbonate \rightarrow Salt + Water + Carbon\ dioxide} \)

Explanation:

• Acid reacts with a carbonate or bicarbonate to produce carbon dioxide gas, which causes effervescence.
• The reaction is used as a test for carbonates — gas turns limewater milky.

Examples:

• \( \mathrm{CaCO_3 + 2HCl \rightarrow CaCl_2 + H_2O + CO_2} \)
• \( \mathrm{NaHCO_3 + HCl \rightarrow NaCl + H_2O + CO_2} \)

Acid Reactions

Laboratory Observations for Each Reaction