When the stopper of the Erlenmeyer flask is loosened before weighing, why doesn't the carbon dioxide escape?
Why isn't the mass of air displaced by the water taken into account when the the mass of water is determined?
a. CO2 is heavier (more dense) than air so it has a tendency to stay at the bottom of the flask.
b. The H2O displaces all of the air; there is no air to take into account.