Lesson Notes By Weeks and Term v4 - SHS 3
INTRODUCTION TO ENGINE TECHNOLOGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
INTRODUCTION TO ENGINE TECHNOLOGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 4
Grade code: 3.1.1.LI.6
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.1
Indicator code: 3.1.1.LI.6
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO ENGINE TECHNOLOGY
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
In our daily lives in Ghana, especially in busy cities like Accra, Kumasi, and Takoradi, we see and smell the smoke coming from the exhaust pipes of cars, 'trotros', and trucks. This smoke contains invisible gases that are harmful to our health and the environment, causing problems like breathing difficulties and smog. Today's lesson is about a very important car part called the catalytic converter, which acts like a small chemical factory in the exhaust pipe. Its job is to clean these harmful gases before they are released into the air we breathe.
A. What is a Catalytic Converter?
A catalytic converter is an exhaust emission control device that is part of a vehicle's exhaust system. Its purpose is to convert toxic (harmful) gases and pollutants from the engine's combustion process into less-toxic pollutants by catalysing a redox reaction (an oxidation and a reduction reaction). Key Term - Catalyst: A catalyst is a substance that speeds up a chemical reaction without being used up or changed in the process. Think of it as a `helper` or a `matchmaker` for chemicals. B. The Problem: Harmful Exhaust Gases
When fuel burns inside an engine, the combustion is never 100% perfect. This incomplete combustion produces three main harmful pollutants: Carbon Monoxide (CO): A poisonous, colourless, and odourless gas. It is dangerous if inhaled because it prevents your blood from carrying oxygen. Unburnt Hydrocarbons (HC): These are small particles of unburnt fuel. They are a major component of smog, the hazy smoke that hangs over cities. Nitrogen Oxides (NOx): This includes gases like Nitrogen Monoxide (NO) and Nitrogen Dioxide (NO2). They are formed when the high temperature in the engine causes nitrogen in the air to react with oxygen. They contribute to smog and acid rain. C. Location and Structure of a Catalytic Converter Location: The catalytic converter is a metal canister located in the exhaust pipeline. It is positioned between the exhaust manifold (which collects gas from the engine cylinders) and the muffler/silencer (which reduces engine noise). It needs to be close to the engine to get hot quickly, as it only works at high temperatures (around 400°C to 800°C).
*Simple Diagram:* `Engine -> Exhaust Manifold -> Catalytic Converter -> Muffler -> Tailpipe -> Atmosphere` Internal Structure: Inside the metal shell, there is a ceramic honeycomb structure called a monolith. This honeycomb structure provides a very large surface area in a small volume. This surface is coated with a thin layer of precious metals which act as the catalysts. Platinum (Pt) and Palladium (Pd): These are oxidation catalysts. Rhodium (Rh): This is a reduction catalyst.