High School Chemistry: Classify Reactions

[Blonde_At_Heart]

I have to decide whether the equation is:

Synthesis

Single Displacement

Double Displacement

Decomposition

Combustion

 

I know what to do for most of them, but one question baffles me. I already filled in the products and balanced the equation (hopefully correctly), and just need to know what type of reaction this is.

 

2 HCl + CaCO3 -> CO2 + H2O + CaCl2

 

I know it isn't synthesis or combustion, and single displacement doesn't sound right. I think it may be double displacement, but decomposition (though there are two reactants) sounds like the most probable answer.

 

Any help would be greatly appreciated

[bob000555]

It’s actually a double replacement then a decomposition:

 

CaCO3 + 2HCl -> CaCl2 + H2CO3

H2CO3 -> H2O + CO2

 

H2CO3(carbonic acid) is a diol acid and thus very unstable decomposing to CO2 and H2O very quickly at room temperature.

[Blonde_At_Heart]

Oh, that makes perfect sense. Thank you so much!