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Rate of reactions

What increases the rate of reaction the most:

Greater Concentration
Catalyst
Higher temperature

Thanks!
Reply 1
Avatar for shengoc
shengoc
12
Original post by Tynos
What increases the rate of reaction the most:

Greater Concentration
Catalyst
Higher temperature

Thanks!


the rate equation provides you this relationship.

rate = A exp (-E/RT)

concentration affects the encounter rate of reacting particles - affects value of A

catalyst affects activation energy, E in this eqn. likewise, T also appears in the exponential part of this eqn. both affects rate exponentially

but then again, different catalyst gives you different activation energy (different pathways with different energies) - how can you tell that one catalyst affects rate of that rxn the most while the other does not - such generalisation is not valid. of course catalysis is always aimed at reducing overall activation energy and making overall rxn faster.
Reply 2
Avatar for Tynos
Tynos
OP
2
Original post by shengoc
the rate equation provides you this relationship.

rate = A exp (-E/RT)

concentration affects the encounter rate of reacting particles - affects value of A

catalyst affects activation energy, E in this eqn. likewise, T also appears in the exponential part of this eqn. both affects rate exponentially

but then again, different catalyst gives you different activation energy (different pathways with different energies) - how can you tell that one catalyst affects rate of that rxn the most while the other does not - such generalisation is not valid. of course catalysis is always aimed at reducing overall activation energy and making overall rxn faster.


Ok what about just temp and conc?
Reply 3
Avatar for BJack
BJack
19
Original post by Tynos
Ok what about just temp and conc?


Again, it depends on the reaction and the extent to which you change the temperature and concentration. There are some reactions with zero activation energy, in which case changing the concentration would be the way to go. Other reactions might have plenty of reactants but not enough energy to overcome the barrier, in which case higher T would be better.

"In general", catalysis is most important and then higher temperature.

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