Does catalyst increase the amount of product?

Question

Chemistry

Answer 1

Catalysts are substances which speed up a reaction. This may lower the energy requirements and so on. It does not increase the amount of production.

Answer 2

no catalyst does not increase the amount of product it just increase the speed of reaction.

Answer 3

NO!!!

Catalyst increase only speed of the reaction

Answer 4

Well, we've established that everybody can read a textbook.

Cindy, do you want the braindead textbook response, or do you want to actually understand some chemistry?

Braindead textbook response: see the other responses.  A catalyst is a substance that accelerates a chemical reaction wihout being consumed by the process.  It acts by lowering the activation barrier.  In other words, it can affect the kinetics -- the reaction rate -- but not the thermodynamics, which determines the amount of product formed at equilibrium.

Fine, go memorize that so you can regurgitate on your test.  Do me a favour, though, and underline the last two words.

Actual chemistry answer: well YES of COURSE it bloody well does.

Look, if your reaction has a half life of 350 years and you run it over the weekend, how much product will you get?  Zero.  If you add a catalyst and the half-life drops to one hour, you'll isolate 100% yield before you leave the lab today and still be home for dinner.  0% yield vs 100% yield, that sounds like an increase in the amount of product to me.  

The problem is that when everybody parrots the textbook and says "no, catalysts don't increase product yield" they forget to finish the sentence: "product yield AT EQUILIBRIUM", a state that many reactions will never achieve in your lifetime without help.  (Your body plus O2 turning into a poof of CO2 NO2 H2O SO3 P4O10 and rust is downhill reaction with a theormodynamic product yield 100%.  Are you bursting into flame?  Nope.)

Half the reactions you're ever going to want to do are thermodynamically favoured, so that the thermodynamic yield should be 100%, but kinetically impossible because the barrier is too high, and the actual practical yield will always be zero, unless you use a catalyst.  In such cases, reactions that are simply impossible without a catalyst, the catalyst increases your isolated product from zero to something above zero.

And here's the other thing: what product?  Often, catalysts lower the barrier via an alternate reaction pathway and the pathway now leads somewhere new!  Often catalysts let you make something that *wouldn't* have been the product otherwise, so you're not just making the product *faster*, you're making a totally *different* product.  In an increased amount, obviously, since you would have had zero without it.  It's one of the coolest things about catalytic chemistry -- not just increased rate, but selectivity to different products.

Example: heat the c**p out of ammonia in air.  Beat on it, high temp, high pressure O2, you'll eventually start generating small amounts of N2 and H2O, which are far and away the thermodynamically most favourable arrangement of those atoms.  Wait long enough, you'll get a quantitative conversion.  Now use a catalyst, do it over hot platinum gauze.  Not only does the reaction time fall from hours to milliseconds, but it's a totally different reaction -- the products, 99+% yield, are NO and H2O, not N2 and H2O.  The catalyst has increased the amount of one of the products (namely nitric oxide).

"You'll increase your yield if you use more catalyst" is not a phrase that any practicing chemist would have any problem with.  Textbook answer: no.  Real answer: oh my goodness yes.

Answer 5

No it increases the rate of the reaction