Understanding Chemical Reactions: From Mg and O2 to CO2 and H2CO3

[ldixon]

We lit a piece of Mg so the formula is:
2Mg(s) + O2(g) HEAT-- 2MgO(s)

We then dissolved this in water so it would then be:
MgO(s) + H2O(l) -- Mg(OH)2(l)

Next we blew into the solution which made it:
CO2(g) + H2O(l) -- H2CO3(l)

Is this all correct? Should I have (Aq) after the H2CO3?

 

[GCT]

Look up the solubility of Mg(OH)2, if it's completely soluble then it may be more appropriate to subscript an "(aq)" term after it. The H2CO3 should be designated with the aqueous symbol.

 

[Blueshift5]

Yes, this is all correct. The reaction between magnesium and oxygen to form magnesium oxide is a classic example of a combustion reaction, where heat is required to initiate the reaction. The resulting compound, MgO, can then react with water to form magnesium hydroxide, which is a base. Blowing into the solution introduces carbon dioxide, which reacts with water to form carbonic acid (H2CO3). The (l) after H2CO3 indicates that it is in liquid form, but it could also be written as (aq) to indicate that it is dissolved in water. Both notations are acceptable. Overall, this is a good demonstration of the various types of chemical reactions that can occur and the importance of balancing equations to accurately represent the reactants and products involved.