State Henry’s Law and Mention Some Important Applications

Answer: According to Henry’s law, the amount of gas dissolved in a liquid is proportional to the partial pressure of the gas. The condition is that the temperature should be constant. Henry’s law constant is the proportionality factor by which the amount of gas and its partial pressure is in proportion. 

The formula for Henry’s law: 

According to this law, P ∝ C. Here, P is the Partial pressure of the gas, and C denotes the concentration of the gas. In certain books, X is used rather than C to indicate the fraction of the gas. 

The formula can also be written as P= kc. Here k, which is the proportionality factor, is called henry’s law constant. 

Application of this law: 

This law was given by William Henry, a renowned physician and chemist of the year 1803.  Till then, this law has been constantly applied in different situations. Several examples of its applications in daily life are given below: 

• Application in respiration: 

Respiration is the process by which we inhale oxygen and exhale carbon dioxide. In this process, the gases we inhale from the atmosphere are dissolved in the blood (a liquid) through alveoli during the gaseous exchange. Now to calculate how much gas is dissolved in our blood, we can apply Henry’s law, and it will be directly proportional to the partial pressure of the gas. 

• Carbonated Soft drinks:

In carbonated soft drinks, carbon dioxide gas is dissolved in a liquid. There exists a difference in the partial pressure of the gas inside the bottle and outside the atmosphere. Due to this difference, we hear a pop sound on opening the bottle. This example also shows how the dissolved gas is proportional to its partial pressure. 

• Deep-sea diving: 

In the deep sea, different gases are dissolved in the water. Due to the difference in the gas pressure on the water’s surface and deep below the surface, the nitrogen starts making blood in veins. Therefore divers have to use oxygen combined with Helium while diving.