Carbon Dioxide in Water

[nothing123]

In the reaction of carbon dioxide and water to form carbonic acid, does water act as a lewis base because it donates a pair of electrons to carbon dioxide or does carbon dioxide act as a Bronsted-Lowry base because it accepts a proton from water?

Thanks.

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[Lotus89]

In the reaction of carbon dioxide and water to form carbonic acid, does water act as a lewis base because it donates a pair of electrons to carbon dioxide or does carbon dioxide act as a Bronsted-Lowry base because it accepts a proton from water?

Thanks.

I am pretty sure it the Bronsted-Lowery base, because it accepted the proton from the water.

 

[sleepy425]

I am pretty sure it the Bronsted-Lowery base, because it accepted the proton from the water.

I disagree. Formation of carbonic acid involves nucleophilic attack by the water oxygen on the CO2 carbon. So the water acts as a lewis base, and the CO2 is a lewis acid. After nucleophilic attack, there is a proton transfer step which involves some typical Bronsted acid/base chemistry, but the first step of the reaction involves no Bronsted acid/base chemistry at all