Equilibrium in Scuba Diving

Scuba divers experience chemical equilibrium in their bodies when they dive. Chemical equilibrium is achieved when the forward and reverse reactions occur at a constant rate. Le Chatelier’s principle states that when a system at equilibrium is disturbed (change in temperature, pressure or concentration) the equilibrium position shifts to counteract the disturbance. Scuba divers have implemented Le Chatelier’s principle to restore equilibrium when there is a change in pressure. We inhale air which is comprised of approximately 20% oxygen and approximately 80% nitrogen along with other gases. At normal atmospheric pressure our body breaks down oxygen and nitrogen. The body absorbs oxygen and small amounts of nitrogen, however, nitrogen cannot be completely dissolved at normal pressure. The body’s ability to intake gases changes when the pressure changes. My equilibrium equation of respiration under pressure:

O2 (g) + N2 (g) 2NO (g)

This is similar to the actual equilibrium equation. It states that oxygen and nitrogen when inhaled dissolve into the body as nitrogen monoxide when the pressure is increased. Nitrogen monoxide decomposes to form oxygen and nitrogen when the pressure is decreased. In the ocean, the pressure is greater at the bottom of the ocean compared to the top. When scuba divers dive, they maintain a constant rate when ascending and descending to allow the body to remain at equilibrium. If the scuba divers ascend or descend rapidly the body will not have enough time to completely dissolve or remove nitrogen from the tissue to achieve equilibrium.


Figure 1.0: Inflamation of the joints due to accumulation of excess gas from rapid shange in pressure.

When the system is under pressure it shifts the equilibrium to reduce pressure. In this scenario there would be a greater absorption of nitrogen in the body. Le Chatelier’s principle is clearly demonstrated by scuba divers on a regular basis as their bodies accommodate to the pressure and reach chemical equilibrium with the inhaled gases. If the body is not properly brought to equilibrium, nitrogen bubbles start to form in the skin, blood vessels, joints and the brain which cause great pain and discomfort.


Figure 1.1: Decompression chamber (restoring body equilibrium by changing pressure gradually outside of the water)

Using Le Chatelier’s principle, the death rate of scuba divers decreased over the years as the divers’ bodies were better able to reach equilibrium with the surroundings. Now, divers are one of the true examples who inherit the concepts of Le Chatelier’s principle in their daily work.


“Boyle’s Law and Scuba Diving.” About.com Scuba Diving. N.p., n.d. Web. 6 May 2013. <http://scuba.about.com/od/Theory/p/Boyles-Law-And-Scuba-Diving.htm&gt;.

“Divers Ill after Clearing River Avon in Chippenham.” BBC News. BBC, 14 Dec. 2011. Web. 6 May 2013. <http://www.bbc.co.uk/news/uk-england-wiltshire-16160432&gt;.

“Under Pressure.” About.com Scuba Diving. N.p., n.d. Web. 6 May 2013. <http://scuba.about.com/od/scuba101/a/Under-Pressure.htm&gt;.

TEIDEMAN, JESS. “A Bad Case Of The Bends.” Australian Geographic 105 (2011): 40-42. Canadian Reference Centre. Web. 6 May 2013.


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5 Responses to Equilibrium in Scuba Diving

  1. mistrynipun4 says:

    This is an excellent application of systems and equilibrium; however, I was wondering if the ocean temperature can shift the equilibrium because generally, as the depth of the water increases the overall temperature decreases. Therefore, does the decrease in temperature have an impact on the equilibrium and would that impact the scuba diver?

  2. nelvin1 says:

    This was a great blog post. Now, you mentioned “When the system is under pressure it shifts the equilibrium to reduce pressure.” We learned in class that when pressure increases, the equilibrium shifts to the side with the least moles. However, based on the given equation “O2 (g) + N2 (g) ⇋ 2NO (g),” the number of moles on both sides is 2. So my question is how does the body (or the thing shifting the equilibrium) know which way to shift equilibrium?

    • The body uses the oxygen which leaves the nitrogen. This is not a complete shift from one side to another but just the concept that the body becomes saturated with unwanted nitrogen gas. If oxygen is removed from the equation the result becomes N2 = N2. Therefore the equilibrium shifts to nitrogen.

  3. ninjapants300 says:

    This is a great example of application of the Le Chatelier’s principal. The ability to further our horizon as humans and expand our knowledge to reach unthinkable accomplishments such as diving is amazing. I find it interesting that the pressure affects the equilibrium, as we know. I’m also curious to know if the temperature of the water has any effect on the equilibrium. If the equilibrium level is not reached nitrogen bubbles begin to form in the body, as you mentioned. I was curious to know whether or not the effects from the nitrogen bubbles leave a lasting injury.

  4. alifaizan786 says:

    Good job!!! on your blog post. I have an important question to ask, as I am just curious and would like to know a little more about this topic. Is inhaling excess amount of Nitrogen harmful for the body? Why do many scuba divers get the “decompression illness”?

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