le Châtelier's Principle: Gas Pressure

Add about a mL of methyl red acid-base indicator to a bottle of carbonated water.   Shake the bottle to mix in the indicator.  The carbonated water is slightly acidic because of the reaction of CO₂ and water, so the indicator is red.   Use a graduated cylinder to measure100 mL of the carbonated water, and add it to a 2 L bottle.  Repeat the procedure, putting 100 mL into each of a 500 mL and a 100 mL bottle.  Now shake the bottles vigorously, which will help them to establish the gas pressure equilibrium quickly.  Notice how the color of the indicator changes.  In the largest bottle it is yellow, in the middle sized bottle a pinkish yellow, while the smallest bottle remains pink.