C8

    Cards (21)

    • Measuring rate
      • Measure how fast the reactants are used up
      • Measure how fast the products are made
    • Measuring rate (practical)
      1. Measure mass lost due to a gas forming using a balance OR
      2. Measure volume of gas made with gas syringe/measuring cylinder and trough of water
      3. Time how long it takes an insoluble product to form
    • What is the procedure to find the instantaneous rate from a graph?
      Draw a tangent at the relevant time and calculate the gradient of the line.
    • What are the key differences between mean rate and instantaneous rate?
      • Mean rate: Average rate across the entire reaction.
      • Instantaneous rate: Rate at a specific point, determined from graphs.
    • Collision theory
      Chemical reactions can occur only when reacting particles collide with each other with sufficient energy
    • Activation energy
      The minimum amount of energy that particles must have to have successful collisions and react
    • C: Increasing surface area
      Means more sites for reaction to occur leading to more frequent collisions
    • C: Increasing temperature
      Causes particles to gain kinetic energy/move faster, so particles collide more frequently and with more energy, meaning a higher proportion will have activation energy
    • C: Increasing concentration
      More particles in the same volume: therefore more frequent collisions
    • C: Increasing pressure
      Squashing gas particles more closely together- more particles of gas in a given space
    • C: Adding a catalyst
      Provides the reaction an alternate pathway, so a greater proportion of particles can now collide successfully, they aren’t used up in reactions
    • RQ: Investigating the effect of concentration on rate of reaction
      This experiment is carried out by measuring the rate of reaction using one of the methods of measuring RR and repeating for different concentrations of a reactant to see the effect
    • Equilibrium
      In a closed system, an equilibrium is reached where the rate of reaction is the same in both directions, so the overall amounts of the reactants and products don’t change.
    • Le Chatelier’s principle
      If the dynamic equilibrium is disturbed by changing the conditions, the position of the equilibrium shifts to counteract the change to re-establish an equilibrium
    • E: Temperature increased
      Equilibrium shifts to favour the endothermic reaction
    • E: Temperature decrease
      Shift to favour exothermic reaction
    • E: Pressure increase
      Shift towards side with smaller number of gas molecules
    • E: Pressure decrease
      Shift towards side with larger number of gas molecules
    • E: Pressure if the number of gas molecules is the same
      No effect
    • E: Concentration decrease
      Shifts to the left to make more reactants react until equilibrium is reached again
    • E: Concentration increase
      Shift towards right to form more products until equilibrium is reached