Question

Would you expect that the amount of \(\mathrm{N}_{2}\) to increase, decrease, or remain the same in a scuba diver's body as he or she descends below the water surface?

Short answer

As the scuba diver descends and the pressure increases, more nitrogen dissolves in his or her body's tissues and blood, increasing the amount of nitrogen in the body.

Step-by-step solution

Understanding Dalton's Law

Dalton's Law states that the total pressure exerted by a mixture of gases is the sum of the partial pressures of each individual gas in the mixture. This means that each gas acts independently, contributing its part to the overall pressure.

Understanding Pressure Changes Underwater

As a scuba diver descends underwater, the pressure on him or her increases due to the weight of the water above part exerting a larger force. This results in an increase in the external pressure, which in turn increases the partial pressure of each gas the diver is breathing, including nitrogen.

Understanding Gas Solubility Under Pressure

According to Henry’s Law, the amount of gas dissolved in a liquid is proportional to the partial pressure of that gas above the liquid. Hence, when the pressure increases, more nitrogen from the breathing gas can dissolve in the body’s tissues and blood.

Conclusion for the Exercise

Considering the above steps, as a scuba diver descends deeper underwater and experiences higher pressure, the partial pressure of the nitrogen in the breathing gas increases and more nitrogen will dissolve in their body's tissues and blood. Hence, the amount of nitrogen in the scuba diver's body would increase.

Key concepts

Dalton's Law

Understanding the pivotal role of Dalton's Law in scuba diving is fundamental. Dalton's Law articulates that within a mixture of gases, like the air we breathe, the total pressure is equivalent to the sum of the pressures that each individual gas would exert if it was alone. This principle becomes especially relevant when we consider a scuba diver's environment, where various gases present in the diver’s tank are under increased pressure due to the depth of the dive.

Consider it like a crowd of people in an elevator; as more people enter, the overall 'pressure' of the crowd intensifies. Each person represents a different gas, contributing to the cramped conditions. For divers, as they descend, the pressure of the surrounding water amplifies, thereby increasing the pressure of each gas in the breathing mix - crucial for understanding diving safety and physiology.

Partial Pressure

The concept of partial pressure is the cornerstone of understanding how gases behave under different conditions in scuba diving. Each gas in a mixture exerts pressure independently as if it were the only gas present; this is known as partial pressure. In the depths of the ocean, the breathing air a diver takes from their tank has increased partial pressures due to the higher ambient pressure.

This ramp-up directly influences gas exchange processes in the body. A useful analogy might be thinking of each gas as a unique music player in a room — even though they are playing simultaneously, we can still distinguish each one's volume (pressure) and how it contributes to the overall noise (total pressure) in the room.

Gas Solubility

Gas solubility is a thermal dynamic principle that underscores how gases dissolve in liquids and is governed by Henry's Law. Simply put, the more pressure exerted on a gas over a liquid, the more of that gas will dissolve into the liquid. When a scuba diver submerges, the increased partial pressure causes more nitrogen, a primary component of air, to dissolve into the diver's blood and tissues.

Imagine soda in a sealed bottle — the carbon dioxide is dissolved in the liquid due to the pressure inside the bottle. Once opened, the pressure decreases and the gas escapes. Similarly, as divers go deeper and the pressure builds, more gas can dissolve into their bodies.

Scuba Diving Physics

Scuba diving physics encompasses the way physical laws, like those of Dalton and Henry, apply to the underwater environment. It is a multifaceted field that considers how pressure changes with depth, gas absorption rates, and buoyancy. For scuba divers, understanding these principles is critical to manage safe ascents and descents.

As divers explore the aqueous depths, their bodies adhere to the laws of physics, responding to the surrounding conditions. Equipped with this knowledge, they can calculate safe stay times at depth and required decompression stops to prevent decompression illness, commonly known as 'the bends.'

Nitrogen Absorption in Divers

Nitrogen absorption in divers is a phenomenon that occurs due to the increased solubility of nitrogen in the body at depth, related to the principles described in Dalton's and Henry's laws. This accumulation can lead to nitrogen saturation in a diver's tissues, which must be carefully managed to avoid decompression sickness upon ascending.

While diving, a diver's body is like a sponge, slowly soaking up nitrogen from their breathing gas due to the elevated pressure. This calls for adequate decompression — akin to gently wringing out the sponge on the way up — allowing safe and gradual release of the absorbed nitrogen.