Rate and extent of chemical change Flashcards
Rate of reaction
amount of product formed or amount of reactant used up / time
For a chemical reaction to take place
Bonds in reactants broken - takes energy
New bonds made when products form - releases energy
Collision Theory
Before particles can react together they must collide with each other, and collisions must have sufficient energy to break bonds in reactants
Activation energy
Minimum amount of energy needed to break bonds in reactants
Rate of chemical reaction can be increased by
Increasing concentration or pressure
Increasing temperature
Increasing SA of reactant
Using a catalyst
Increasing conc (or pressure for gases)
Increased conc - increased no of particles in a certain vol - more successful collisions per second - rate of reaction increases
or increased pressure - particles closer together - more successful collisions per second - rate increases
Increasing temperature
increasing temp transfers more energy to particles and they move faster - more successful collisions per second
increasing temp gives particles more energy - more collisions will be successful as more particles have energy higher than activation energy
Increasing SA
larger SA - more particles of solid exposed - more collision at surface - more successful collisions per second - higher rate
Using a catalyst
catalysts provide a different pathway for a reaction with lower activation energy - higher proportion of particles have energy to react per second - rate increased
DO NOT produce more collisions per second or increase energy of particles
Reversible reactions
some reactiosn can react to form both forward and backward direction
reactants react to form products and products can react again to form reactants
energy released when reaction goes in one direction = energy taken in opposite direction
dehydration of hydrated copper(ii) sulfate
add water to copper sulfate, hydrated copper sulfate forms (blue)
remove water from copper sulfate, anhydrous copper sulfate is formed (white)
effect of heat on ammonium chloride
when heated ammonium chloride splits into hydrogen chloride and ammonia
these can be reacted to form ammonium chloride
dynamic equilibrium
occurs in a closed system with the forward and backwards reactions happening at equal rates. concentrations of reactants and products remain equal
le chatelier’s principle
if we change/disturb conditions of a reversible reaction qt equilibrium, then the equilibrium will move/shift to counteract the change
le chats principle // temp
increasing temperature favours endothermic reaction
Heat favours ENdo
