Oxygen is commonly collected using the downward displacement of water. This method works because oxygen is less dense than water and only slightly soluble in it. The process involves collecting the oxygen gas produced in a reaction in an inverted container filled with water. As the oxygen gas is produced, it rises and displaces the water.
Laboratory Collection Methods
Downward Displacement of Water
- This is a standard laboratory technique.
- It leverages the lower density and slight solubility of oxygen in water.
- Oxygen gas bubbles upwards, displacing the water in a collection vessel. See figure 1 in this experiment for a visual representation.
- This method is described in multiple sources: Oxygen Collection Over Water - YouTube, Name the method of gas collection that can be used in collecting oxygen gas in the laboratory give reason, and 4: The Properties of Oxygen Gas (Experiment) - Chemistry LibreTexts.
Other Collection Methods
While downward displacement of water is common in laboratory settings for small-scale oxygen collection, industrial-scale oxygen production uses different techniques:
- Cryogenic Distillation: Large-scale air separation plants utilize cryogenic distillation to separate oxygen from other components of air. Learn more about commercial oxygen production.
- Oxygen Concentrators: These devices concentrate oxygen from ambient air by removing nitrogen using a sieve. More details on oxygen concentrators.
Water Sample Collection for Oxygen Analysis
The collection of water samples for oxygen analysis, such as measuring dissolved oxygen, requires a specific procedure to prevent contamination and maintain sample integrity. The EPA outlines this procedure for titration using the Winkler method.
