Rate and Extent of Chemical Changes

• Rate of reaction is how fast a reaction happens, measured in seconds per mole of reactants
• Steeper the line of a graph, the faster the rate of reaction
• Reaction Rates are explained by particle collision theory
• The more collisions, the faster a reaction
• Reaction rates depend on 4 things : Temperature, Concentration of the Solution, Surface Area and the presence of a catalyst
• When temperature is increased, particles move faster
• The faster a particle moves, the more energy it has
• If a solution is more concentrated, there are more particles in the same volume
• Smaller pieces of a solid are more likely to collide than a larger peice of solid
• Catalysts: A substance that increases the rate of a chemical reaction without being used up in the reaction
• Enzymes are biological catalysts
• Reversable Reactions will reach equilibrium
• As reactants react, their concentrations fall so the forward reaction will slow down
• At equilibrium, both reactions are still happening at the same rate but there is no effect
• Equilibrium can only happen in a closed system so no products can escape
• If equilibrium lies to the left, the reactant is more concentrated than the product
• If equilibrium lies to the right, the reactant is more concentrated than the product
• The position of equilibrium depends on temperature, pressure and concentration
• Reversable Reactions can endothermic or exothermic
• Anhydrous means without water
• Le Chatelier's principle: If a system is in equilibrium, any change in the conditions will result in a change in the position of equilibrium
• All reactions are exothermic in one direction and endothermic in the other
• If you decrease the temperature, equilibrium will move towards the exothermic reaction and you get more products for the exothermic reaction and fewer for the endothermic reaction
• If you increase the temperature, equilibrium will move in the endothermic direction and you get more products for the endothermic reaction than the exothermic
• Changing pressure only affects equilibrium with gasses present
• Increase in pressure moves equilibrium towards the side with fewer molecules.
• Decreasing pressure moves equilibrium towards the side with more molecules.
• Increasing the concentration of reactants increases the amount of product formed
• Decreasing the concentration of products decreases the amount of reactants