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Collision theory and reaction rate effects

The rate and extent of chemical change • Rate of reaction

Key concepts

What you'll likely be quizzed about

  • Collision theory states that particles must collide to react.
  • Only collisions with sufficient energy and correct orientation create products.
  • The reaction rate depends on the number of collisions per unit time and the proportion of those collisions that are effective.

Flashcards

Test your knowledge with interactive flashcards

What is the limiting factor when increasing concentration has little effect?

Click to reveal answer

The limiting factor is the fraction of collisions with sufficient energy or proper orientation; if few collisions are effective, rate increases are limited.

Key notes

Important points to keep in mind

Collision frequency is proportional to concentration in solutions and number density in gases.

Only collisions with energy greater than or equal to activation energy and correct orientation are effective.

Temperature increases average kinetic energy and the fraction of effective collisions; higher rates are often observed with increased temperature.

Pressure changes affect gas collision frequency but do not modify activation energy.

Doubling concentration typically doubles rate for simple collision-limited reactions; proportionality is influenced by reaction order.

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