Complete Guide to Year 11 Chemistry Module 4 - Drivers of Reactions

Introduction

Module 4: Drivers of Reactions is the last module you’ll need to learn before you enter the world of Year 12 HSC Chemistry! This is where you’ll build your foundational knowledge in preparation for the next four modules of high school chemistry. Namely, the key concepts we’ll explore are Enthalpy, Entropy, & Gibbs Free Energy

A lot of people say that Year 11 “doesn’t really matter” since it doesn’t count towards the HSC, but I’d argue that regardless, it’s still vital that you build the basics in this year before moving on – a house with foundations is stronger than one without!

In this guide to Module 4 of Prelim Chemistry, I’ll provide a summary of the key concepts you need to understand to ace this module and hopefully by the end, you’ll like chemistry just a little bit more than you already do.

Enthalpy 

Energy is always being exchanged, whether that be in chemical reactions, or even in everyday life. The food you eat is turned into energy for your body to use to move, solar panels turn solar energy into useful electrical energy – there are millions of examples in the universe, but in Chemistry, we focus on the energy exchanged within chemical reactions through the breaking and formation of bonds. Such energy is measured using something known as enthalpy, which is defined as a measure of the total heat (energy) of a system.

Bond breaking & formation

Think about two strong magnets that are magnetised together. Pulling them apart is going to require a lot of force (or energy), whilst putting them back together will actually move your hands with the magnets as they snap together. We can think about the force pulling them apart as inputting energy into the “system,” and putting them back together as releasing energy.