Venusian atmosphere is supercritical at lower altitudes
The atmosphere of Venus is 96.46% carbon dioxide. Carbon dioxide goes supercritical when both pressure is over 74 bars and temperature is over 303 deg.K. This condition is satisfied on Venus at altitudes less than 3.5 km. One could think of Venus as having an ocean of supercritical carbon dioxide with an average depth of 3.5 km (the Earth's oceans have greater depths). Supercritical carbon dioxide is a potent solvent and funky material. Do a google on it and you'll find there's heaps written about it. Chemistry on the Venusian surface must be very strange.
Gary