反応速度

How fast, and why

• The rate of reaction 反应速率 is how fast reactants turn into products.
• For particles to react, they must collide.
• But not every collision works.

Effective collisions 有效碰撞

• An effective collision has enough energy and the correct direction — so a reaction happens.
• A non-effective collision lacks energy or hits at the wrong angle — nothing happens.
• The rate depends on the frequency of effective collisions per second.

At higher temperature the curve spreads to the right, so a larger fraction of molecules can react

Concentration 浓度 and pressure

• Increasing concentration (or gas pressure) packs particles closer together.
• They collide more often, so there are more effective collisions per second — the rate rises.

A catalytic converter speeds up reactions that clean a car's exhaust gases

Measuring rate in the lab

• Follow a reaction by gas volume, mass loss, or a colour/conductivity change over time.
• The initial rate is the gradient of the tangent at the start.

More particles in the same volume collide more often, so the rate rises

You've got it