Problem 131 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is an example of absorption? (a) Oxygen on metal surface (b) Hydrogen on finely divided nickel (c) Water on calcium chloride (d) Water on silica gel

Step-by-Step Solution

Answer

(c) Water on calcium chloride is absorption.

Step 1: Identify the concept

Before solving the problem, we need to understand the difference between adsorption and absorption. Adsorption is the process where molecules are held on the surface of a solid or liquid. Absorption is a process where a substance is taken up and distributed throughout the bulk of the material.

Step 2: Analyze the options

Let's evaluate each option to determine whether it represents adsorption or absorption. 1. Oxygen on metal surface - This is adsorption, as oxygen sticks to the surface. 2. Hydrogen on finely divided nickel - This is adsorption, occurring when hydrogen adheres to the nickel's surface. 3. Water on calcium chloride - This describes absorption, as water is absorbed and reacts with calcium chloride. 4. Water on silica gel - This is adsorption, where water molecules accumulate on the surface of silica gel.

Step 3: Select the correct option

From our analysis, option (c) 'Water on calcium chloride' represents absorption, as the water is taken in and used within the calcium chloride, unlike the other options, which are examples of adsorption.

Key Concepts

Adsorption

Adsorption is a fascinating phenomenon where molecules from a substance adhere to the surface of another material. It differs significantly from absorption, as adsorption occurs strictly at the surface level.

Imagine small sticky particles attaching themselves to an object's exterior. This process is paramount in many applications and scientific fields, including:

• Catalysis: Enhancing chemical reactions by offering a surface for reactions to occur.
• Filtration: Removing pollutants from air or liquids by trapping them on filter surfaces.
• Adsorbent Materials: Utilized in products like activated charcoal to purify substances.

Adsorption is generally influenced by factors such as surface area, temperature, and pressure. The larger the surface area or the lower the temperature, generally, the higher the adsorption potential. Understanding these dynamics helps engineers and scientists design efficient systems for environmental and industrial processes.

Chemical Reactions

Chemical reactions are processes where substances, known as reactants, transform into new substances, called products. They are central to many scientific disciplines and are responsible for the myriad of natural and industrial processes we observe daily.

Key aspects of chemical reactions include:

• Reaction Types: Such as synthesis, decomposition, single replacement, and double replacement reactions.
• Kinetics: The study of reaction rates and the factors affecting them, like temperature and concentration.
• Catalysts: Substances that increase the rate of a reaction without being consumed in the process, facilitating adsorption.

Chemical reactions often involve energy changes, where bonds are broken and formed, leading to either the release or absorption of energy. Whether witnessing a combustion reaction or the rusting of iron, chemical reactions are constantly reshaping the world.

Chemistry Concepts

Chemistry is a branch of science focusing on substances and their interactions. Central to chemistry are concepts such as atoms, elements, compounds, and the periodic table, which help us classify and understand matter.

Fundamental chemistry concepts include:

• Atomic Structure: Comprising protons, neutrons, and electrons, defining the characteristics of elements.
• Covalent and Ionic Bonds: Essential for forming compounds, each with unique properties.
• Moles and Molar Mass: Important for quantitative chemistry, relating the mass of substances to their chemical quantity.

Understanding these concepts allows us to delve into more complex topics, like organic chemistry and biochemistry, bridging microscopic atomic behaviors with macroscopic phenomena we encounter. Mastering the basic chemistry concepts sets a solid foundation for exploring the diverse and fascinating chemical processes that govern both living and non-living systems.