The notation 10-²⁴ bar (or formulated 1.E-24)in connection with oxygen concentration refers to an extremely low partial pressure of oxygenin a given environment. Here’s a detailed explanation:
- Notion of oxygen partial pressure
The partial pressure of a gas in a mixture represents the pressure it would exert if it were alone in the same volume. It is often expressed in bar (or Pascals, 1 bar = 100,000 Pa).
By way of comparison, ambient air contains around 21% oxygen, and atmospheric pressure is around 1 bar. So, the partial pressure of oxygen in normal air is
1 x 0.21 = 0.21 bar
- Meaning of 10-²⁴ bar
- A pressure of 10-²⁴ bar means an extremely low oxygen concentration.
- To give an order of magnitude, this pressure is trillions of times lower than the partial pressure of oxygen in air.