Which gas evolves

[typicalindian]

How are we supposed to go about answering these types of questions? Is there some systematic approach to them? I still don't really understand it.

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[MedPR]

Experience and probably solubility rules sometimes. For instance, alkane + heat + O2 = CO2 gas evolves always.

 

[typicalindian]

Experience and probably solubility rules sometimes. For instance, alkane + heat + O2 = CO2 gas evolves always.

right but that's just a simple combustion reaction, I'm referring to the somewhat obscure ones where the passage will just tell you that they mixed a bunch of crap and BAM some gas evolves

 

[MedPR]

I don't think there are any hard and fast rules. Do you have a specific example?

 

[typicalindian]

I don't think there are any hard and fast rules. Do you have a specific example?

if you still have AAMC access, take a look at AAMC 8 passage 6 in PS, # 40

 

[MedPR]

I'm not sure why A, B, or D are wrong, but whenever I did these problems and saw CO2 as an answer choice, I picked it unless there was no way CO2 could be formed. There's carbonate, and acid in the mixture. Acid + Carbonate = carbonic acid (H2CO3) and you know from physiology that there is an equilibrium between H2CO3 and CO2+H2O.

Again, I can't tell you why A, B, or D are wrong, but whenever these types of questions pop up I pick CO2 if I can think of a way CO2 could be made.

 

[pfaction]

Is that the one with nickel and carbonate? Exactly what you said. I saw that Carbonate + HCL -> Auto CO2.