Please help: CaCO3+Zn-->??

[pnonso]

Hi. Does anybody know what CaCO3+Zn+heat will produce? Thanks a lot for any help!

[hotcommodity]

Look in your text for an activities chart. If Zn is stronger than Ca, Zn will accpet the anion that Ca has. If not, no reaction will occur.

[woelen]

Well, things may turn out different, than one just could say on the basis of the activities series. The latter is not really applicable in situations where solid mixtures are heated.

 

I can imagine that the Zn can reduce the carbonate ion when sufficient heat is applied and if that indeed happens, I expect the following:

 

Zn + CaCO3 --> ZnO + CaO + CO

[chemhero]

I'll go with zinc reducing aswell - its used in the lab all the time in inorganic reactions as a reductant (itself oxidised! OilRig!).

 

Matt

[hotcommodity]

Well, things may turn out different, than one just could say on the basis of the activities series. The latter is not really applicable in situations where solid mixtures are heated.

 

I can imagine that the Zn can reduce the carbonate ion when sufficient heat is applied and if that indeed happens, I expect the following:

 

Zn + CaCO3 --> ZnO + CaO + CO

 

I assume Zn will accept an O because of how its valence electrons are ordered, but the above reaction leads me to two questions: 1) how can you predict the electron dot structure of a transition metal? and 2) would every Zn ion react with every one out of three oxygen ions, and if not, wouldnt that lead to a reversible reaction?

[woelen]

Ad 1) This depends on the electronic structure of the element itself. For transition metals, however, things are more diffuse, because they can exist in multiple oxidation states (zinc is an exception, however) and because they can form complexes with many things.

 

Ad 2) Not all oxygens will be bonded to zinc. Calcium will not be set free in this reaction, it will also remain in the +2 oxidation state, requiring an oxygen atom. Carbon also certainly will not be set free, but at the high temperatures involved, CO2 is not likely to occur. If that would occur, then we would have simple decomposition of chalk, without oxidation of zinc. Hence the expectation of CO, CaO and ZnO.

[YT2095]

I`m also in agreement with Woelen here, CO2 will be produced initially but as the temp rises it also will split, leaving CO to escape, the carbonates of both calcium and zinc are easily destroyed with heat, you`ll never rip that oxygen off though, not without some Serious reducing power in there and/or extreme heat.

[chemadict]

Its possible, thats what they sometimes do to produce CO in labs, Zn + CaCO3 => ZnO + CaO + CO