rates of reaction

• What does it mean when the position of equilibrium is to the right?

  It means that the amount of reactants and products are equal.
• What is the rate of a reaction?

  It is how fast the reactants are used up or how fast the products are made.
• What is Collision Theory in chemical reactions?

  • Reactions occur when particles collide with a minimum amount of energy (activation energy).
  • More successful collisions lead to a higher rate of reaction.
• How does increasing the temperature affect the rate of reaction?

  It causes particles to move faster and collide more successfully.
• What happens to the rate of reaction when the concentration of a gas is increased?

  The rate of reaction increases due to more particles in the same volume.
• How does increasing the surface area of a solid reactant affect the reaction rate?

  It increases the chance of collisions, leading to a higher rate of reaction.

  the surface area to volume ratio is increased allowing for more places for collisions to happen
• What is a catalyst?

  A catalyst is a substance that speeds up reactions without being used up.
• How do catalysts increase the rate of reaction?

  They lower the activation energy needed for the reaction to start.
• What are the factors affecting the rate of reaction?

  • Increasing temperature
  • Increasing concentration
  • Increasing surface area
  • Using a catalyst
• What is the relationship between successful collisions and the rate of reaction?

  More successful collisions per second lead to a higher rate of reaction.
• What does breaking a solid reactant into smaller pieces do?

  It increases the surface area for reactions to take place.
• What is the effect of a catalyst on the activation energy of a reaction?

  A catalyst provides an alternative pathway with lower activation energy.
• what is a reversible reaction


  where the products can react again to form the reactants
• as the reactants react, their concentrations fall, so the forwards reaction slows down. as more products are being made and their concentrations rise, the backwards reaction will speed up
• equilibrium 


  when the forwards and backwards reaction are going at exactly the same rate
• dynamic equilibrium


  at equilibrium both reactions are still happening but there is no overall effect, meaning the concentration of reactants and products have reached a balance and wont change
• closed systems


  equillibrium can only be reached if the reaction takes place in a closed system. a closed system means that none of the products can escape and no reactants can get in
• equillibrium lying to the right

  concentration of products is greater than that of the reactants
• equillibrium lies to the left

  concentration of the reactants is greater than that of the products
• position of equillibrium depends on

  • temp
  • pressure
  • concentration
• le chateliers principle


  the idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract the change
• le chatelier increased temp

  • all reversible reactions are endothermic in one direction and exothermic in the other
  • if you increase the temperature, the mixture aims to decrease it- therefore endothermic reaction is favoured and the equilibrium will move in the endothermic direction. you will now get more products for the endothermic reaction and less products for the exothermic reaction
• le chatelier decreased temp

  if you decrease the temperature, the mixture aims to increase it- therefore the exothermic reaction is favoured and the equilibrium will move in the exothermic direction, meaning more products for exo and fewer for endo
• le chatelier change to pressure


  • only effects equilibrium involving gases
  • use the balanced symbol equation to see which side has more gas molecules
  • if u increase pressure the mixture aims to decrease it- moves in the direction where there are fewer gas molecules
  • if u decrease pressure it aims to increase it- moves in the direction where there are more gas molecules
• le chatelier change to concentration


  • if u increase concentration of the reactants, the system aims to counteract it by making more products