The purpose of this module is to develop your understanding of a range of chemical reactions and improve your skills in writing and balancing chemical equations. This module seeks to assist you in gaining an understanding of why certain elements are more reactive than others and the factors which affect reactivity for different types of reactions.
All chemical reactions involve the creation of new substances and associated energy transformations, which are commonly observable as changes in the temperature of the surroundings and/or the emission of light. These reactions are harnessed and controlled by chemists to produce substances that lead to the development of useful products.
Chemicals can react at many different speeds and in many different ways, yet they basically involve the breaking and making of chemical bonds. In this module, you will study how chemicals react, the changes in matter and energy that take place during these reactions and how these chemical reactions and changes relate to the chemicals that are used in everyday life.
There are three main areas of content:
Chemical Reactions
Predicting Reactions of Metals
Rates of Reactions
Through these areas of content, you will have the opportunity to explore the following questions:
1) What are the products of a chemical reaction?
2) How is the reactivity of various metals predicted?
3) What affects the rate of a chemical reaction?
It is important to understand that a single chemical reaction can meet the classification criteria for several different types of reactions.
As an example: You can classify an orange as a sphere, a fruit, orange-coloured, rough-surfaced, internal-seeded, but you might just be interested in mentioning it as a sphere to contrast with a cube, so you wouldn't bother with all the other characteristics.
2Mg + O2 --> MgO is synthesis, combustion, exothermic, redox...but you might only be interested in it as an example of a synthesis reaction at a particular time.
TEXT REFERENCE: CHAPTER 10
There are basically two types of changes: physical and chemical.
Chemical changes occur when a new substance is formed. This is also called a chemical reaction. We begin with one or more reactants and we end with one or more products.
Reactants --> Products
The new substance or substances will often have different properties to the reactants. They may be a different colour or state. The reactions are not easily reversed (usually) and chemical reactions are often accompanied by large energy changes, which can include heat or light or even sound.
In any chemical reaction, bonds within the reactants are broken and then new bonds are formed in creating the products. Energy is required to break chemical bonds and energy is released when bonds are formed. Hence a chemical reaction is also a transfer of energy.