Absorption (chemistry)

Some things can soak up other things.

It is like a sponge. The stuff goes deep inside. It does not stay on top. This is called absorption.

Some things soak up water. This can happen in solids. It even happens in living things.

Some things soak up air. This can happen in a liquid. It can also happen in a solid. This can change energy too.

Clothes can soak up water. Even dry cloth has some water. This helps people make fabric. It is a very useful way for things to work.

Absorption is a way that things soak up other things.

When a substance is absorbed, it goes deep inside. It enters the bulk phase of a material. This means it fills the whole volume. It does not just stay on the surface. This is different from adsorption. In adsorption, things only stay on the surface.

There are two main ways this happens. One way is physical absorption. This does not cause a chemical change. For example, water can soak into some solids. This happens because of polar interactions.

The other way is chemical absorption. This is also called reactive absorption. It happens when a chemical reaction occurs. The two things change when they meet. This often happens in tall columns. These columns can be plate or packed columns.

Absorption can also change energy. It can capture and transform power. In the textile industry, people study how fibers soak up water. Even dry cloth holds some water. This is called moisture regain. Scientists can measure this by heating the fiber in an oven. This makes the fiber lose weight.

Absorption is a way that substances soak up other things.

It happens when atoms, molecules, or ions enter a material. These particles go into the bulk phase of the material. The bulk phase is the whole volume of the substance. This is different from a process called adsorption. In adsorption, particles only stay on the surface. In absorption, the substance is taken up through the whole body. This process can even capture and transform energy.

There are two main ways this works. One way is called physical absorption. This happens without a chemical reaction. In this way, a substance moves from one phase to another. For example, you can extract a solute from one liquid to another. Noble gases and osmium tetroxide can do this. The other way is chemical absorption. This is also called reactive absorption. It involves a chemical reaction between the two substances. This type of absorption depends on the concentration of the reactants.

Scientists use many tools to study these changes. For chemical absorption, they often use special equipment. These are called plate columns or packed columns.

In gas absorption, people can use the Ideal gas law. This law helps them calculate concentration. They might also use partial pressures instead. If the process is physical, it might follow the Nernst distribution law. This law uses a constant called a partition coefficient. This value changes depending on the temperature. It helps show the ratio of concentrations in two different phases.

Many different materials show these effects in real life. Hydrophilic solids can readily absorb water. These are solids that like water, including many biological materials. This happens because of polar interactions. These interactions allow the solid to soak up water vapor. Even in low humidity, these solids can take in water. This can happen in many different units. Different types of phase flows can also happen during these interactions.

We can see absorption in things we use every day. Think about the clothes you wear. Fibers are often hydrophilic materials. Even if a fiber feels dry, it usually contains some water. The textile industry calls this moisture regain. This is the proportion of a material's weight made of water. You can measure this by using an oven. Heating the fiber drives the water off. This causes a measurable decrease in the weight. If the fiber goes back to a normal atmosphere, it will regain that weight.

Absorption is a fundamental process in chemistry and physics. It occurs when atoms, molecules, or ions enter the bulk phase of a material. This bulk phase can be a gas, a liquid, or a solid. It is important to distinguish absorption from a similar process called adsorption. In adsorption, particles only stick to the surface of a material. In absorption, the particles are taken up into the entire volume of the substance.

This distinction is vital for understanding how materials interact with their environment. Absorption can even involve the capture and transformation of energy.

There are two primary ways that absorption occurs: physical and chemical. Physical absorption is a non-reactive process. In this type, a substance moves from one phase to another without a chemical reaction. For example, scientists can perform liquid-liquid extraction to move a solute between liquids. Noble gases and osmium tetroxide are examples of substances that can be extracted this way. Chemical absorption is also known as reactive absorption. This occurs when a chemical reaction happens between the absorbing substance and the substance being absorbed.

Reactive absorption depends on the concentration of the reactants and the stoichiometry of the reaction.

When absorption is a purely physical process, it often follows the Nernst distribution law. This law describes the ratio of concentrations of a solute in two different bulk phases. When these phases are in contact and at equilibrium, this ratio remains constant. This constant value is called the partition coefficient, noted as KN. The value of this coefficient depends on the temperature of the system. This law is valid if the concentrations are not too high. It also requires that the species does not change its form in either phase.

If a molecule undergoes association or dissociation, the law still describes the equilibrium for that specific form.

In industrial settings, chemical absorption is often used to replace physical processes. A common example is the absorption of carbon dioxide by sodium hydroxide. Because this is an acid-base process, it does not follow the Nernst partition law. To manage these reactions, engineers use specialized equipment. These units are often called plate columns or packed columns.

These columns allow for different types of phase flows and interactions. In the case of gas absorption, scientists can calculate concentration using the Ideal gas law. They might also use partial pressures to find these values.

Many solids exhibit a strong ability to absorb water. These are known as hydrophilic solids. Many biological materials are hydrophilic. This happens because of polar interactions between the water and the molecules of the solid. These interactions favor the partition of water into the solid. Because of this, these materials can absorb significant amounts of water vapor. This can happen even when the humidity in the air is relatively low.

We can observe the effects of absorption in the textile industry. Most fibers are hydrophilic materials. Even when a fiber feels dry to the touch, it usually contains some water. This phenomenon is known as moisture regain. Moisture regain is the proportion of a material's weight that consists of water. Scientists can measure this by using an oven to heat the fiber. The heat drives the water off, which causes a measurable decrease in weight.

If the fiber is returned to a normal atmosphere, it will gradually regain that weight.

Understanding absorption is essential for many scientific fields. It connects to concepts in physical chemistry, gas technologies, and the study of gases. The term "sorption" is a broader term used to cover absorption, adsorption, and ion exchange. By studying how substances enter the bulk phase of others, we can better understand how energy and matter move through our world.