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Kinetics

Effect of Concentration and Pressure, and Catalysts

  • 3 things to know
  • Papers 2 and 3

Overview

Collision frequency, and how a catalyst provides an alternative route of lower activation energy.

What you need to know

Answer each one before you reveal it.

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Key term

How does increasing the concentration of a reactant affect collision frequency?

Key term

Why does increasing concentration increase the rate of a reaction?

Key term

How does increasing the pressure of a gaseous reaction mixture affect collision frequency?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    How does increasing the concentration of a reactant affect collision frequency?

    Model answer

    Increasing the concentration of a reactant increases the collision frequency between particles.

  2. 2

    Why does increasing concentration increase the rate of a reaction?

    Model answer

    More collisions per unit time means more collisions with energy equal to or greater than the activation energy, so more successful collisions occur per unit time.

  3. 3

    How does increasing the pressure of a gaseous reaction mixture affect collision frequency?

    Model answer

    Increasing the pressure of a gaseous reaction mixture increases the collision frequency between gas particles.

  4. 4

    Why does increasing pressure increase the rate of a reaction involving gases?

    Model answer

    Higher pressure means gas particles are closer together, leading to more frequent collisions and therefore more successful collisions per unit time.

  5. 5

    For a reaction in solution, what happens to the collision frequency if the concentration of one reactant is doubled?

    Model answer

    The collision frequency approximately doubles.

  6. 6

    For a gaseous reaction, what happens to the collision frequency if the pressure is halved?

    Model answer

    The collision frequency decreases as particles are further apart on average.

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