( In a tube ) why CO2 gas doesn't sinks (gets below) , displacing the water to be on the top, If carbon dioxide (44 g/mol) has more molar mass than water( 17 g/mol)? Is it just because water is a liquid and co2 is a gas or there are some other factors?

i have read in my book that CO2 released from some reaction can be collected using displacement of water (as it is slightly soluble in water) and it is collected above the jar thus lowering the water level, so why water is below and CO2 is above if co2 has molar mass than water?

1 Answer
Aug 21, 2017


Density of the substance stratifies into layers with the less dense on top of the more dense .


Density of #CO_2# = 1.978 g/Liter at ~#25^oC# and water in liquid form at the same temperature is ~1000 g/Liter. Formula weights of the substances do not stratify into layers, density difference does.
Hot air balloons rise into the atmosphere because the density of hot air is less than the surrounding cooler air, and so goes all immiscible substances at different densities.