L1.1: Reaction Rate

• Kinetics

  The study of the rates of chemical reactions and the factors that affect those rates.

  ● Provides an understanding on how fast a reaction occurs and why it happens at that speed.

  ○ How fast does a reaction proceed?
• Reaction Rate

  ● The change in concentration of reactant or product with time. (M/s)

  ○ Faster reaction (higher rate), reactant concentration decreases quickly.

  ○ Slower reaction (lower rate), reactant concentration decreases slowly.
• Factors Influencing Reaction Rate

  1. Concentration
  2. Physical State
  3. Temperature
  4. Catalyst
• Physical State

  1. Substances must mix to collide.
  2. Reactants in the same phase of matter (like aqueous solutions), collide due to the natural, unpredictable motion of molecules, wherein gentle stirring mixes them more thoroughly and therefore reacts faster.
  3. Reactants in a different phase of matter, contact only at the interface between phases, therefore vigorous stirring or grinding may be needed to produce collisions, thereby producing reactions– albeit at a slower rate.
  4. Interface means the surface where two different materials touch each other. Like if you pour oil into water, the interface is the surface where the oil and water meet.
• Temperature

  1. Molecules must collide with enough energy.
  2. High temperatures give molecules high kinetic energy, increasing collision frequency, and thereby increasing reaction rate.
  3. Low temperatures give molecules low kinetic energy, decreasing collision frequency, and thereby decreasing reaction rate.
• Catalyst

  1. Existence of one, speeds up reaction processes.