Activation Energy (Ea): It's like a hill that reactions need to cross over.

• Definition: The minimum kinetic energy (Ek) particles need to have for a reaction to take place.

Imagine a ball at the bottom of a hill. On its own, the ball won't make it over. Push it with some energy, and voilà! It rolls down the other side. Here

• Hill's height = Activation Energy (Ea)
• Difference in elevation (start to finish) = Reaction Enthalpy (ΔHr)

Important Points

• If the combined kinetic energy (Ek) of colliding particles < Ea → No reaction, no matter how they crash into each other!
• If Ek ≥ Ea → Reaction can happen if the particles bump into each other the right way.

It's like the path a reaction follows with ups and downs.

• Horizontal Axis: Reaction progress (reactants to products).
• Vertical Axis: Energy at each stage.
• Exothermic Process: Energy is given out (ΔHr < 0) – like warming your hands with a hot pack.
• Endothermic Process: Energy is absorbed (ΔHr > 0) – like how an ice pack feels cold.

Transition State: The top of our reaction hill!

• It's the highest energy point and least stable.
• Where some old bonds break and new ones aren't fully formed yet.
• Think of it as a roller coaster's highest point – scary and unstable!

Temperature changes how molecules move and crash into each other!