1) why arent they consumed in the reaction ( can you explain step by step how it influences the reaction?)
2) is it energy related?
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TLDR; Lowers activation energy meaning it kicks off chemical reactions like you light up paper so the flames start spreading. Example for mechanism, scroll down to ethanol synthesis
So chemical reactions work with energy. If a chemical reaction happens, it either relesses energy (meaning the outcome is more stable) or takes it (you basically force a reaction that doesn’t want to happen). This basically is how your smartphone battery works. If you charge it, you give it electrical energy. The chemicals take this energy to react and form less stable things (that have higher energy). Using your smartphone releases the energy
This happens by a reaction that forms more stable chemicals, the energy is given off.
But every reaction still need energy to kick off the reaction. Imagine a hill with a ball on it. The higher sits, thr higher it’s energy. If the ball can, he will just roll down and decrease it’s energy. But our hill has a small incline! So in order to roll down you actually need to give it a little kick or else ir just sits there uphill. We call this kick the “activation energy (lets abbrecviate it to AE) “, the energy required to start the reaction.
It is also known that the speed of a chemical reaction is directly dependent on the activation energy.
For many reactions, the AE is very low, so it happens instantly. For many others, it is very high. This is the reason why we don’t just ignite in air. Even though we could. The energy to start the burning reaction is waaayy to high.
Catalysts choose a different reaction pathway that loerrs the activation energy. So chemical reactions happen thaz otherwise woukd not have kicked off. Because the molecules seek the lowest energy, the start following whatever the catalyst is doing. It’s as if the catalysts bores a hole through the little incline. But as a trade off, thr ball has to get green, because the boring machine is full of green paint.
So not only do we have thr ball at the ground level now. Something that requires a big kick off (like heat).But it is also green, something that could have never happend without the boring machine, even with heat.
For your other question, here is the synthesis of ethanol as an example (not really used, but you can do it).
H2C=CH2 + H2O -> H3C-CH2OH
This reaction doesn’t happen. Unless we catalyze that with sulfuric acid.
H2SO4 -> HSO4- + H+ (our catalyst was just used)
H2C=CH2 + H+ -> H3C-CH2+
H3C-CH2+ + H2O -> H3C-CH2OH + H+
HSO4- + H+ -> H2SO4 (our catalyst is back)
This is of course a bit simplified, but you see that we get back the catalyst in the reaction and it’s ready to do this exact same process roughly 10^23 times.
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