# Is carbon dioxide more acidic than carbon monoxide?

Which of the given compounds is most acidic? $$\ce{CO}$$ or $$\ce{CO2}$$ ?

How do I solve this question, and how do I explain it?

I took the oxidation state of carbon in both. The oxidation state in $$\ce{CO2}$$ is higher, therefore it is more electronegative, so therefore $$\ce{CO2}$$ may be more acidic.
For $$\ce{CO }$$ I don't know about the charge so that I can use it to understand if it would give electron or accept electrons, so that I can apply Lewis acid/base theory.

Carbon dioxide is a much stronger Lewis acid than carbon monoxide. In carbon dioxide, the carbon has a much higher oxidation state (formally, $+4$ vs. the $+2$ of carbon monoxide), and the two oxygen atoms heavily withdraw electron density from the carbon atom, leaving a very large partial positive charge ($\delta^{+}$). This is rigorously confirmed by electrostatic potential maps and calculated orbital coefficients. As a consequence, the electron-deficient carbon of $\ce{CO2}$ is highly electrophilic, and reacts with a variety of nucleophiles (e.g., Grignard reagents, organolithium reagents, etc.).