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Acids and Bases - Neutralization Reactions

Grade 9IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Neutralization is a chemical reaction where an H+H^+ ion from an acid reacts with an OH−OH^- ion from a base to form water (H2OH_2O).

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The general word equation for a neutralization reaction is: Acid+Base→Salt+WaterAcid + Base \rightarrow Salt + Water.

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If the base is a carbonate, the reaction also produces carbon dioxide: Acid+Carbonate→Salt+Water+CO2Acid + Carbonate \rightarrow Salt + Water + CO_2.

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The identity of the salt depends on the acid used: HClHCl forms chlorides, H2SO4H_2SO_4 forms sulfates, and HNO3HNO_3 forms nitrates.

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The net ionic equation for the neutralization of a strong acid and a strong base is always H+(aq)+OH−(aq)→H2O(l)H^+(aq) + OH^-(aq) \rightarrow H_2O(l).

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During neutralization, the pHpH of the acidic solution increases towards 7, while the pHpH of a basic solution decreases towards 7.

📐Formulae

Acid+Base→Salt+H2OAcid + Base \rightarrow Salt + H_2O

H+(aq)+OH−(aq)→H2O(l)H^+(aq) + OH^-(aq) \rightarrow H_2O(l)

Acid+Metal Carbonate→Salt+H2O+CO2Acid + Metal\ Carbonate \rightarrow Salt + H_2O + CO_2

HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l)

💡Examples

Problem 1:

Write the balanced chemical equation for the reaction between sulfuric acid (H2SO4H_2SO_4) and potassium hydroxide (KOHKOH).

Solution:

H2SO4(aq)+2KOH(aq)→K2SO4(aq)+2H2O(l)H_2SO_4(aq) + 2KOH(aq) \rightarrow K_2SO_4(aq) + 2H_2O(l)

Explanation:

Sulfuric acid is a diprotic acid, meaning it releases two H+H^+ ions. Therefore, it requires two molecules of potassium hydroxide (which provides one OH−OH^- each) to be fully neutralized, forming potassium sulfate and water.

Problem 2:

Predict the products and write the balanced equation for the reaction between hydrochloric acid (HClHCl) and calcium carbonate (CaCO3CaCO_3).

Solution:

2HCl(aq)+CaCO3(s)→CaCl2(aq)+H2O(l)+CO2(g)2HCl(aq) + CaCO_3(s) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)

Explanation:

When an acid reacts with a metal carbonate, it produces a salt (calcium chloride), water, and carbon dioxide gas. The reaction is balanced by placing a coefficient of 2 in front of HClHCl to account for the two chlorine atoms in CaCl2CaCl_2.

Problem 3:

What is the salt produced when nitric acid (HNO3HNO_3) reacts with magnesium oxide (MgOMgO)?

Solution:

Mg(NO3)2Mg(NO_3)_2 (Magnesium nitrate)

Explanation:

The cation comes from the base (Mg2+Mg^{2+}) and the anion comes from the acid (NO3−NO_3^-). To balance the charges, the formula for the salt is Mg(NO3)2Mg(NO_3)_2.

Neutralization Reactions - Revision Notes & Key Formulas | IB Grade 9 Science