Gas forming reaction?

[PAyankee]

Hello, i have a question about a practice problem I ran across in topscore and can't figure out based on the explanation it gave. You're given BaCO3(s)+ HCl (aq)----> and you have to figure out if it is gas forming or not and what the sum of the coefficients for the net ionic equation are. The net ionic equation given in the answers is BaCO3 + 2H ----> H20+ CO2+Ba +2 .

How do you get the ionic equation and determine it is gas forming?

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[herkulease]

First you need to balance the reaction.

BaCO3(s)+ 2HCl (aq) --> BaCl2(aq) + H2CO3(aq)

H2CO3(aq) is carbonic acid which readily decomposes to Water and Carbon Dioxide.

So now you rewrite it as

BaCO3(s) + (2H+) + (2Cl-) ----> (Ba2+) +(2Cl-) + H2O(l) + CO2(g)

now you just cancel out what is the same on both side and you get your answer.

As for how do you know if something will be a gas or not. You just need to know certain certain aqueous solutions decompose into a gas.

Carbonic Acid is one. Another is hydrogen peroxide which becomes water and O2

 

[Fletcher Moore]

As for how do you know if something will be a gas or not. You just need to know certain certain aqueous solutions decompose into a gas.

Carbonic Acid is one. Another is hydrogen peroxide which becomes water and O2

Questions that involve gas formation are always a guess for me. I tend to guess based on what I think is the most common gas of the answer choices. Not surprisingly, this strategy is hit or miss.

Unfortunately, it has been I think ~8-9 years since I took inorganic chemistry. Are there any kind of rules to predict reaction products, or do you just need to memorize the common ones?

My suspicion is oxyacids + acid -> gas derived from the oxyacid, but I cannot find confirmation or anything more detailed.