That's a bit tricky! You're likely thinking about a reaction involving carbon monoxide (CO) and water (H₂O).

Here's the breakdown:

* Carbon monoxide (CO) is a poisonous gas.

* Water (H₂O) is a common liquid.

When carbon monoxide reacts with water under certain conditions (like high temperature and a catalyst), it produces carbon dioxide (CO₂) and hydrogen gas (H₂):

CO + H₂O → CO₂ + H₂

This reaction is known as the water-gas shift reaction. It's important in industrial processes for producing hydrogen.

Let me know if you have any other chemistry questions!