WAEC Chemistry

Chemistry is a vital subject in the WAEC exams, and understanding common chemistry reactions can greatly enhance your performance. Over the years, certain types of reactions frequently appear in WAEC Chemistry past papers. This article will guide you through some of these common reactions, ensuring you are well-prepared for your exams.

Acid-Base Reactions

One of the most recurrent types of reactions in WAEC Chemistry exams is acid-base reactions. These involve the reaction between an acid and a base to form a salt and water. For example:

• Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) → Sodium chloride (NaCl) + Water (H₂O)
• Sulfuric acid (H₂SO₄) + Potassium hydroxide (KOH) → Potassium sulfate (K₂SO₄) + Water (H₂O)

In your preparation, it's essential to understand the properties of acids and bases, as well as how to balance these equations. You can find comprehensive lesson notes and practice questions on acid-base reactions on the Green Bridge CBT platform.

Redox Reactions

Redox (reduction-oxidation) reactions are also common in WAEC Chemistry exams. These reactions involve the transfer of electrons between two species. Oxidation refers to the loss of electrons, while reduction is the gain of electrons. Examples of redox reactions include:

• Zinc + Copper sulfate → Zinc sulfate + Copper
• Iron + Oxygen → Iron oxide

Understanding redox reactions requires a good grasp of oxidation states and the ability to identify which species are oxidized and reduced in a reaction. The Green Bridge CBT platform offers past questions and answers that can help you master these concepts.

Precipitation Reactions

Precipitation reactions occur when two aqueous solutions react to form an insoluble solid called a precipitate. This type of reaction often appears in WAEC Chemistry past papers. For example:

• Silver nitrate (AgNO₃) + Sodium chloride (NaCl) → Silver chloride (AgCl) + Sodium nitrate (NaNO₃)
• Lead(II) nitrate (Pb(NO₃)₂) + Potassium iodide (KI) → Lead(II) iodide (PbI₂) + Potassium nitrate (KNO₃)

To prepare, practice identifying which compounds precipitate under various conditions. Detailed lesson notes and practice materials available on the Green Bridge CBT platform will help you excel in this area.

Combustion Reactions

Combustion reactions involve the reaction of a substance with oxygen to produce oxides and release energy, usually in the form of heat and light. Such reactions commonly feature in WAEC Chemistry examinations. Examples include:

• Combustion of methane: CH₄ + 2O₂ → CO₂ + 2H₂O
• Combustion of ethane: 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Familiarize yourself with different types of combustion reactions and their products. Utilizing resources from Green Bridge CBT can provide beneficial insights on this topic, including lesson notes and tutorial videos.

For additional support, you can access past questions, detailed lesson notes and a variety of other resources on Green Bridge CBT's mobile app. Preparing thoroughly with these common chemistry reactions and leveraging the resources at Green Bridge CBT will give you the best chance to succeed in your WAEC exams.