Chemical Reactions Flashcards
What is an exothermique reaction and why is it the way it is
A reaction that releases heat into the environment. This is because more energy is created when bonds are made than energy needed to break the bonds for the reaction.
What is an endothermic reaction
A reaction that uses heat from the environments making it colder. This is because the energy needed for break the bonds in the reactants is greater than the amount of energy released when new ones are made.
What are the 3 factors affecting rate of reaction
Surface area
Concentration
Temperature
What is collision theory
For a reaction to occur, the reactant particles must collide with enough energy break the bonds and start the reaction
How does concentration effect rate of reaction
Higher the concentration, the greater the reaction speed. This is because the higher the concentration, the more reactant particles there are in a given volume meaning collisions are more likely and frequent. This increases the rate of reaction.
How does temperature effect rate of reaction
The hotter it is, the more kinetic energy the reactant particles have, this means they are travelling faster to more likely to collide as well as have enough energy to cause the reaction.
How does surface area effect the rate of reaction
The greater the surface area of, the more exposed reactant particles there are. This means collisions are more frequent thus increasing rate of reaction. If there was a low surface area, only the particles on the surface could react and the ones under wouldn’t be able to until the ones above had reacted.
What is a catalyst
A substance that increases rate of reaction without being used up.
Why are catalysts important
They increase rate of reaction
They reduce temperature and pressure needed for the reaction meaning less energy is needed for it so it is cheaper.
What does a catalytic converter do in a car
Combustion takes place in a car and the exhaust contains harmful carbon monoxide. Catalytic converters increase rate of reaction between oxygen in the air and carbon monoxide to make carbon dioxide.
What about the design of a calatytic converter makes it so good
Energy though it is small, its honeycomb structure gives it a very large surface area to increase rate of reaction more
Metals platinum, rhobidium and palladium which is used in catalytic converters is expensive so it is applied very thinly.
