Reaction Rates 3

3.1 Introduction

ESCAQ

Before we begin this section, it might be usefulto think about some different types of

reactions and how quickly or slowly they occur. See introductory video:VPmvq at

http://www.everythingscience.co.za

Exercise 3 - 1

Think about each of thefollowing reactions:

• rusting of metals


• photosynthesis


• weathering of rocks (e.g. limestone rocks beingweathered by water)


• combustion

1. For each of the reactions above, write a chemical equation for the reaction that
   takes place.


2. How fast is each ofthese reactions? Rank them in order from the fastest to the
   slowest.


3. How did you decidewhich reaction was thefastest and which was the slowest?


4. Try to think of someother examples of chemical reactions. How fastor slow is
   each of these reactions,compared with those listed earlier?

More practice video solutions or help at http://www.everythingscience.co.za

(1.) 01pv (2.) 0243 (3.) 0244 (4.) 0245

In a chemical reaction,the substances that areundergoing the reactionare called the

reactants, while the substancesthat form as a result ofthe reaction are calledthe

products. The reaction rate describes how quicklyor slowly the reaction takes place.

So how do we know whether a reaction is slowor fast? One way of knowing is to look

either at how quickly the reactants are used up during the reaction orat how quickly

the product forms. For example, iron and sulphur react according to the following

equation: