Explain how CO2 can cross a cells plasma membrane

Normally we think of CO2 as a gas because it is (at least when its in the atmosphere it is). However, it is a very different story inside of cells. CO2 is produced as a result of respiration inside mitochondria but if it remained a gas this could have potential lethal consequences for an organisim like humans. Instead CO2 is soluble to some extent in water and, being uncharged, can cross the plasma membrane via simple diffusion. In animals the CO2 gradient is maintained by a moving blood supply and in plants its simply difuses out into the atmosphere where the concentration is extemely low at about 0.03%.