Acid and bases

Acids and Base Reactions - Neutralization

What is an acid?

Acids are substances that taste sour. eg. citric acid. They turn blue litmus paper pink. There are many different types of acids and most are too corrosive to taste. The word corrosive means it will eat away.

Acids always produce salts when they react with chemical substances.

Acid	Chemical formula	Salt produced	Ion
Hydrochloric acid	HCl	chloride salt	Cl^-
Nitric acid	HNO₃	nitrate salt	NO₃^-
Sulfuric acid	H₂SO₄	sulfate salt	SO₄^2-
Acetic acid	CH₃COOH	acetate salt	CH₃COO^-
Phosphoric acid	H₃PO₄	phosphate salt	PO₄^3-

Acids produce hydrogen or H⁺ ions in solution.

What is a base?

Bases are substances that taste bitter. eg. Bi-carb of soda. They turn pink litmus paper blue. Soluble bases produce alkali solutions. These solutions are caustic and will burn or corrode organic matter.

Common bases include metal hydroxides, metal oxides and ammonia.

Base	Chemical formula
Sodium hydroxide	NaOH
Potassium hydroxide	KOH
Ammonia	NH₃
Calcium oxide	CaO
Magnesium hydroxide	Mg(OH)₂
Sodium oxide	Na₂O

Bases produce hydroxide or OH^- ions in solution.

What is an alkali?

An alkali is a strong soluble base. All of the Group I metals or alkali metals produce alkali solutions on reaction with water. eg. lithium hydroxide LiOH, sodium hydroxide NaOH and potassium hydroxide KOH.

Alkali solutions are caustic in nature and should be handled with care. Dilute alkali solutions are slippery to touch.

What is a neutralization reaction?

Acids and bases react with each other to produce salt and water.

This type of chemical reaction is called a neutralization reaction.

The general equation for a neutralization reaction

Acid + Base Salt + Water

A common neutralization reaction carried out in high school is the reaction of hydrochloric acid with sodium hydroxide.

Hydrochloric acid + sodium hydroxide Sodium chloride + Water

HCl + NaOH NaCl + H₂O

All neutralization reactions are also exothermic meaning heat is given off. Hydrogen ions produced from the acid react with hydroxide ions produced from the base. Energy is released as new chemical bonds are formed as water is produced.

Hydrogen ion + hydroxide ion water

H⁺(aq)+ OH^-(aq) H₂O(l)

Chemical Formula for Common Acids, Alkalis and Bases

Click on the chemical name to show the chemical formula of the acid or base.

Note: An alkali is a soluble base and is caustic in nature.

The chemical formula for a range of acids and bases

HCl Hydrochloric acid	H₂SO₄ Sulfuric acid	HNO₃ Nitric acid	CH₃COOH Acetic acid	Acids
HBr Hydrobromic acid	HF Hydrofluoric acid	H₂CO₃ Carbonic acid	H₃PO₄ Phosphoric acid	Acids
NaOH Sodium hydroxide	KOH Potassium hydroxide	LiOH Lithium hydroxide	NH₃ Ammonia	Alkalis
Na₂O Sodium oxide	K₂O Potassium oxide	Li₂O Lithium hydroxide	Na₂CO₃ Sodium carbonate	Alkalis
Mg(OH)₂ Magnesium hydroxide	Al(OH)₃ Aluminum hydroxide	CuO Copper(II) oxide	NiO Nickel(II) oxide	Bases

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Identification of Salts

Can you identify the salt produced from each acid base combination?

Click on the salt link to show or hide the chemical name.

Salts produced from acid base reactions

Sodium hydroxide	Potassium hydroxide	Magnesium hydroxide	Calcium oxide
sodium chloride salt?	potassium chloride salt?	magnesium chloride salt?	calcium chloride salt?	Hydrochloric acid
sodium nitrate salt?	potassium nitrate salt?	magnesium nitrate salt?	calcium nitrate salt?	Nitric acid
sodium acetate salt?	potassium acetate salt?	magnesium acetate salt?	calcium acetate salt?	Acetic acid
sodium sulfate salt?	potassium sulfate salt?	magnesium sulfate salt?	calcium sulfate salt?	Sulfuric acid
sodium phosphate salt?	potassium phosphate salt?	magnesium phosphate salt?	calcium phosphate salt?	Phosphoric acid

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Examples of neutralisation reactions

Acids reacting with metal hydroxide bases

1. Sulfuric acid + sodium hydroxide sodium sulfate + water

H₂SO₄ + 2NaOH Na₂SO₄ + H₂O

2. Nitric acid + potassium hydroxide potassium nitrate + water

HNO₃ + KOH KNO₃ + H₂O

3. Sodium hydroxide + nitric acid sodium nitrate + water

NaOH + HNO₃ NaNO₃ + H₂O

4. Hydrochloric acid + magnesium hydroxide magnesium chloride + water

2HCl + Mg(OH)₂ MgCl₂ + 2H₂O

5. Potassium hydroxide + acetic acid potassium acetate + water

KOH + CH₃COOH CH₃COOK + H₂O

Acids reacting with metal oxide bases

1. Sodium oxide + nitric acid sodium nitrate + water

Na₂O + 2HNO₃ 2NaNO₃ + H₂O

2. Hydrochloric acid + calcium oxide calcium chloride + water

2HCl + CaO CaCl₂ + H₂O

3. Potassium oxide + phosphoric acid potassium phosphate + water

3K₂O + 2H₃PO₄ 2K₃PO₄ + 3H₂O

4. Aluminum oxide + hydrochloric acid aluminum chloride + water

Al₂O₃ + 6HCl 2AlCl₃ + 3H₂O

5. Barium oxide + hydrochloric acid barium chloride + water

BaO + 2HCl BaCl₂ + 2H₂O

Neutralisation Equation Worksheets

Identification of salts from a variety of acid reactions

Balancing of neutralization reactions

Interactive Chemistry Worksheets for Students

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