rate and extent of chemical change

• chemical reactions only occur when the reacting particles collide with each other with the sufficient energy
• increasing temperature increases the average speed of particles which means more collisions happen per second increasing the chance that there is enough energy for a reaction to take place
• if the concentration of one of the reactants is increased then the number of successful collisions also increase as there are more particles available to collide with
• if we increase the surface area of the solid reactant then there are more particles available to react so the number of successful collisions will increase
• catalysts lower activation energies but do not affect equilibrium
• a catalyst speeds up the rate of reaction without being used itself
• catalysts are not included in the chemical equation because they are not used up
• in a reversible reaction the products can react to create the original reactants
• in reversible reactions, if a solution is endothermic in the forward reaction it will be exothermic in the reverse reaction
• reversible reaction example: solid ammonium chloride decomposes when heated to produce ammonia and hydrogen chloride gas- ammonia reacts with hydrogen chloride to produce clouds of white ammonium chloride
• in a closed system no reactants are added and do products are removed.
• when a reversible reaction occurs in a closed system, an equllibrium is achieved when the rate of the forward reaction is equal to the rate of the backwards reaction