Rate Of Reaction Flashcards
(12 cards)
What do rates or chemical reactions tell us
How quickly reactants are converted into products
Fast reactions
Often better as they yield more product in an amount of time
However it is expensive to generate conditions for these fast reactions and they often come with safety concerns
How to calculate rate of reaction at specific time on graph
Place tangent on graph and work out gradient
What does collision theory explain
How reactions happen and why they Happen at different rates
Collision theory: particles collision
Particles must collide for chemical reactions to happen and these collisions must happen with enough energy
What is the minimum amount of energy to start a chem reaction called
Activation energy
Collision theory: rates of reaction
U can increase rate of reaction by increasing the frequency of collisions and or energy of reactant particles
Factors that effect rate of reaction
Conc of dissolved reactant - increasing conc increases collision frequency
Pressure of gass reactants - increasing pressure increases collision frequency
Temperature - increases the energy reactant particles
Surface area of solid reactants - increasing surface area increases collision frequency
Catalysts - substances that increase chemical reactions rate without reducing in quantity
Catalysts
Increase rate if reaction by lowering the activation energy
They cannot be used up so aren’t found in chemical equations and can be reused
Eg
Iron used in process to make ammonia
Enzyme catalyse reactions ij biological systems
Often come as pellets powders because these types of substance have particularly high surface areas
Advantages of catalysts
Often cost effective a small amount can speed up a reaction a lot
Fewer fossil fuels need to be burned as catalysts reduce the nessasary temps and pressures for chemical reactions
Disadvantage of catalyst
Many are toxic and can escape into the environment and contaminate ecosystems
