reaction rates and equilibrium

• Rate of reaction

  The change in concentration of a reactant or a product in a given time.
• Limiting reagent

  The reactant that is not in excess which will be used up first and stop the reaction
• Adsorption

  The process that occurs when a gas or liquid or solute is held to the surface of a solid
• Anhydrous

  Containing no water molecules
• Catalyst

  A substance that increases the rate of a chemical reaction without being used up in the process. A catalyst provides an alternative route for the reaction with lower activation energy
• Desorption

  Release of an adsorbed substance from a surface
• heterolytic fission

  the breaking of a covalent bond forming a cation (positive ion) and an anion (negative ion)
• reaction rate equation

  rate = change in concentration (mol dm^-3) / time (s)
• factors affecting rate:

  • concentration
  • pressure
  • surface area
  • temperature
  • catalyst
• if a gas is produced, 2 methods to determine the rate of reaction:

  • measuring the volume of gas produced at regular time intervals using gas collection
  • monitoring the loss of mass of reactants using a balance
• why is a catalyst sustainable?

  • reduces temperature and energy requirements
  • less fossil fuels used which cuts CO2 emissions
• how are catalysts of economic importance?

  makes products faster and uses less energy cutting costs and increasing profitability
• Two reasons why using a lower temperature due to a cataluyst is beneficial to the environment:

  1. Less fossil fuel used
  2. Reduction in CO2 (emissions)
• One advantage and one disadvantage of monitoring loss of mass compared to the gas collection method

  1. Advantage: no loss of gas
  2. Disadvantage: small loss in mass
• Dynamic equilibrium exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction. Concentrations do not change over time.