5.3 Catalysts Flashcards
What are catalysts
Why are they used
Substances that increase rate of reaction without being chemically changed themselves at the end of the reaction
It is cheaper to use a catalyst to speed up rate of reaction rather than use higher temperatures and pressures
How do they work
They provide a different pathway to reaction, one with lower activation energy so they therefore reduce activation energy for reaction
What are catalytic converters
Found in car engines
Honeycomb shape covered in platinum or rhodium catalyst
The shape provides large surface area for reactions to occur
How do catalytic converters work
Polluting gases pass over the catalyst and they react with each other to produce less harmful products
2CO + 2NO —> N2 + CO2
Hydrocarbons + Nitrogen oxides —> Nitrogen + CO2 + H2O
How do the reactions take place on surface of catalyst
1) Gases form weak bonds with catalysts metal ions and are adsorbed onto surface of catalyst
This makes the gases in the right position to react with each other
2) The products then break away from metal atoms and desorb from surface, which frees up room on catalyst for more gases to take their place and react
