What does selectivity of a catalyst mean?

Question

What does selectivity of a catalyst mean?

Answer 1

Selectivity of a catalyst is its ability to to direct a reaction to yield a particular product.eg H2 (srry dont know how to get subscript) and CO react to give

1)CH4 +H2O in presence of Ni

2)CH3OH in presence of Cu/ZnO-Cr2O3

3)HCHO in presence of Cu

Answer 2

Selectivity of a catalyst means that a particular catalyst is particularly suited to change the reaction rate of a specific reaction. If you use the wrong catalyst in  a reaction, you will not get the results you expect.

As an example, for ammonia production the catalyst used is based on iron. In the oxidation of SO2 → SO3 in the production of H2SO4, the catalyst is vanadium pentoxide, V2O5. You cannot use V2O5 the produce NH3. The catalysts are selective to the particular reactions.

Answer 3

catalyst is a kind of softball bat, but other then that I have no idea what you are talking about.. sorry!

Answer 4

Catalysts increase the rate of (catalyze) reactions.  One  might increase the rate of reaction of acid and alcohol to form an ester, for example.  

The selectivity is a way of talking about how widely, or narrowly, the action of the catalyst is defined.   On what reactants does it work?   Does it work on all aliphatic acids, but not on aromatic ones?  Maybe it's selective for alcohols less than five carbons in size.  Maybe it's selective for only one pair of reactants.  Or has low selectivity and catalyzes any pair you can find.   Selectivity can be useful if there's one reaction you'd like to promote, but other possible reactions that you'd rather not have happen.

Answer 5

The selectivity of a catalyst is its ability to direct a reaction to yield preferentialy a particular product. e.g.

CO  + 3H2  ----->   CH4  +  H2O  ( Ni catalyst)

CO  +  H2   ------>   HCHO            (Cu catalyst)