Background
Redox reactions involve two or more chemicals where oxidation states of two or more atoms or ions involved change. (Often it may also involve exchange of oxygen.) The species that undergoes reduction in oxidation state is said to have undergone reduction and labeled as the oxidizing agent. The species that undergoes increase in oxidation state is said to have undergone oxidation and labeled as the reducing agent. Complex redox reactions, involving three or more chemicals are the basis for fireworks. The beautiful colors produced are a result of emission of light by electronic transitions within different transition metals found in the compounds used.
Resources: (PowerPoint slides to be found on my homepage.)
- Core & Extension Chemical Reactions Redox II: Oxygen Definition
- Extension Chemical Reactons Redox II: Electron Definition
- Extension Chemical Reactions Redox III: Oxidation State
Discrepant Event
(This discrepant event appears in both MYP and IB Diploma.)
In the video below, IB Diploma students in one of my former schools and myself are playing with fire crackers and making observations in an effort to understand the chemistry of fire crackers. Watch the video to see what they do and the various different demonstrations performed.
And the questions are:
- Find some firecracker ingredients and their reactions. Balance them.
- Using one of the various methods available, in terms of redox, identify the reducing agent(s) and oxidizing agent(s).
- What do you notice about the products of a reaction in a fire cracker?
- In the demonstration towards the end of the video, a fire cracker was set off under an inverted tin can. Why did the can fly up into the air? (Hint: Use your answer to question 3.)
Concepts involved:
- reduction, oxidation, reducing agent, oxidizing agent.
- chemical equation, chemical reaction.
