Question

Which of the following is used as a dessicant in the laboratory? (1) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) (2) anhydrous \(\mathrm{CaCl}_{2}\) (3) \(\mathrm{II}_{2} \mathrm{SO}_{4}\) (4) \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

Short answer

Anhydrous \(\mathrm{CaCl}_{2}\) is used as a desiccant in the laboratory.

Step-by-step solution

Understand the Role of a Desiccant

A desiccant is a substance that is used to absorb moisture from the air and keep the surrounding environment dry. Identify which among the given options is known for strong moisture absorption.

Analyze Each Option

(1) \ \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) is sodium carbonate, commonly used in applications such as water softening and as a water-soluble base, but it's not known primarily as a desiccant.(2) Anhydrous \(\mathrm{CaCl}_{2}\) is calcium chloride without water; it is highly hygroscopic and is commonly used as a desiccant.(3) \ \(\mathrm{II}_{2} \mathrm{SO}_{4}\) appears to be a typographical error; assuming it should be \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (sulfuric acid), it is a strong acid, and while concentrated, it can be hygroscopic, it is not typically categorized as a desiccant.(4) \ \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) is calcium phosphate, commonly used in fertilizers, and does not have hygroscopic properties to be used as a desiccant.

Identify the Correct Answer

Based on the analysis, anhydrous \(\mathrm{CaCl}_{2}\) (calcium chloride) is the most suitable option among the given choices, as it is well-known for its moisture-absorbing properties and is commonly used as a desiccant in laboratories.

Key concepts

desiccants

Desiccants are vital substances in various fields, especially in laboratories. They are used to absorb moisture from the air, ensuring that the environment remains dry. This is crucial in many scientific experiments and processes where even trace amounts of water can affect results. Common desiccants include silica gel, calcium chloride, and molecular sieves. These materials have a high affinity for water molecules and can absorb significant amounts of moisture relative to their weight. Desiccants are often found in small packets in food packaging, pharmaceuticals, and electronics to prevent moisture-induced damage.

laboratory chemicals

Laboratory chemicals are substances used for conducting scientific experiments and research. They come in various forms, such as liquids, solids, gases, and solutions. These chemicals need to be pure and of analytical grade to ensure accurate results. Examples include acids like sulfuric acid, solvents like ethanol, and bases like sodium hydroxide. Proper handling and storage of these chemicals are essential to maintain their integrity and to ensure safety in the lab. Many laboratory chemicals are hygroscopic and require desiccants in storage to prevent them from absorbing moisture from the air.

hygroscopic substances

Hygroscopic substances have the ability to absorb water from their surrounding environment. This property makes them useful in various applications, particularly in maintaining dry conditions. Examples include calcium chloride, sodium hydroxide, and certain salts. These substances can absorb moisture even at relatively low humidity levels. Their hygroscopic nature is often leveraged in producing products like concrete, to combat moisture, or in food preservation, to extend shelf life. Understanding the hygroscopic properties of substances is key in selecting the right materials for moisture control applications.

moisture absorption

Moisture absorption refers to the process by which materials take in water vapor from the atmosphere. This can be critical in preventing moisture-related issues such as mold growth, corrosion, and degradation of materials. Effective moisture absorption is achieved using desiccants like silica gel and anhydrous calcium chloride. In laboratory settings, moisture absorption must be carefully monitored to ensure the accuracy of experiments and the longevity of equipment and reagents. Technologies leveraging moisture absorption include dehumidifiers and moisture absorptive packaging, both of which help control and reduce ambient moisture levels.