chemical change Flashcards
what catalyst is used to make ammonia?
iron
what catalyst is used in catalytic converters in cars?
platinum and palladium
what is a catalyst?
a substance that increases rate of reaction without getting used up, (though sometimes has to be cleaned)
how does a catalyst work?
lowers rate of reaction by lowering activation energy by providing an alternate reaction pathway, therefore more particles have enough energy to collide and react frequency of successful collisions increases Different reactions need different catalysts
advantages of fast reactions
more product in given time less fuel needed (if catalyst used)
disadvantages of fast reactions
catalysts or conditions may be expensive there can be safety concerns catalyst may be toxic
increasing temperature in reactions
increases rate of reaction: giving particles more energy therefore more have activation energy and more kinetic energy therefore they move quicker thus increased frequency of collisions
increasing pressure/concentration in reactions
increases rate of reaction: more particles in less area thus increased frequency of collisions
increasing surface area
increases rate of reaction: giving more area with which to collide with thus increased frequency of collisions
reversible reaction
the products of the reaction can react to produce the original reactants If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction. The same amount of energy is transferred in each case.
collision theory
chemical reactions can occur only when reacting particles collide with each other and with sufficient energy
activation energy
minimum amount of energy that particles must have to react
dynamic equlilibrium
When a reversible reaction occurs in a closed system (apparatus which prevents the escape of reactants and products) equilibrium is reached when the forward and reverse reactions occur at exactly the same rate
Le Chatelier’s Principle
If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
change of concentration in reversible reactions
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again
