Topic 6- Rate & Extent of Chemical Change

• What is the rate of reaction?

  The rate of reaction is the measurement of time it takes for reactants to be used or converted into products
• What is collision theory?

  For chemical reactions to occur there must be successful collisions between particles. They must also have enough energy to do so.
• What is the calculation for the rate of reaction?

  amount of product formed / amount of reactant used

  -------------------------------------------------

  time taken
• What are the 4 factors affecting the rate of reaction?

  Temperature, concentration or pressure of gas, surface area, and catalysts.
• What is activation energy?

  The minimum amount of energy required for a reaction to occur
• Why does increasing the temperature increase the rate of reaction?

  The particles will have more energy and move faster which means they collide more frequently.
• Why does increasing the concentration increase the rate of reaction?

  There will be more particles (higher volume) to react with, meaning there will be more collisions.
• Why does increasing the surface area increase the rate of reaction?

  Increased collision frequency between reactant particles.
• What is a catalyst?

  A substance that increases the rate of a chemical reaction without being consumed in the process.
• Why does using a catalyst increase the rate of reaction?

  They lower the activation energy.
• Name a biological catalyst.

  Enzymes - they catalyse reactions in living things.
• What are the ways of measuring the rate of reaction?

  Change in concentration, precipitation and colour change, change in pressure, change in volume.
• What are the 2 rate experiments?

  Magnesium + HCL to produce H2 gas

  Sodium thiosulfate + HCL to produce a cloudy precipitate
• What is a reversible reaction?

  A reaction that can proceed in both the forward and backward directions. (reactants into products and products into reactants)
• What's it called when a reversible reaction is going at the same rate?

  Dynamic equilibrium.
• What is a closed system?

  A closed system is a system where no reactants or products can escape or enter.
• What type of reactions can reversible reactions be?

  Endothermic and exothermic reactions
• What are Le Chatelier's principles?

  temperature changes, pressure and concentration.