Overview
This lecture introduces the concepts of spontaneous and non-spontaneous chemical reactions in thermodynamics and discusses factors influencing reaction spontaneity.
Spontaneous Reactions
- A spontaneous reaction occurs without needing external energy input.
- Example: Rusting of iron (iron reacts with oxygen to form Fe₂O₃) is a spontaneous process.
- Spontaneous reactions happen naturally under given conditions.
Non-Spontaneous Reactions
- A non-spontaneous reaction requires external energy to proceed.
- Example: Returning rusted iron back to pure iron (restoring a rusty car) is non-spontaneous.
- Non-spontaneous does not mean impossible; it just needs energy input.
Preventing Spontaneous Reactions
- Mechanical barriers, like paint or wax, can stop oxygen from reaching iron and prevent rusting.
- Lowering the temperature can slow down or prevent spontaneous reactions by affecting reaction kinetics.
Key Terms & Definitions
- Spontaneous Reaction — A chemical reaction that occurs naturally without outside energy.
- Non-Spontaneous Reaction — A chemical reaction that requires external energy to proceed.
- Oxidation — A chemical process where a substance gains oxygen, as when iron turns to rust (Fe₂O₃).
- Kinetics — The study of reaction rates and how they can be influenced.
Action Items / Next Steps
- Review examples of spontaneous and non-spontaneous reactions.
- Think about ways to prevent unwanted spontaneous reactions in real life.