Problem 22 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The correct match between Item I and Item II is: Item I \(\quad\) Item II (A) Benzaldehyde (P) Mobile phase (B) Alumina (Q) Adsorbent (C) Acetonitrile (R) Adsorbate (a) \((\mathrm{A}) \rightarrow(\mathrm{Q}) ;(\mathrm{B}) \rightarrow(\mathrm{P}) ;(\mathrm{C}) \rightarrow(\mathrm{R})\) (b) \((\mathrm{A}) \rightarrow(\mathrm{R}) ;(\mathrm{B}) \rightarrow(\mathrm{Q}) ;(\mathrm{C}) \rightarrow(\mathrm{P})\) (c) \((\mathrm{A}) \rightarrow(\mathrm{Q}) ;(\mathrm{B}) \rightarrow(\mathrm{R}) ;(\mathrm{C}) \rightarrow(\mathrm{P})\) (d) \((\mathrm{A}) \rightarrow(\mathrm{P}) ;(\mathrm{B}) \rightarrow(\mathrm{R}) ;(\mathrm{C}) \rightarrow(\mathrm{Q})\)

Step-by-Step Solution

Answer

The correct match is option (b): (A) → (R), (B) → (Q), (C) → (P).

Step 1: Understanding the Terms

We have three items (A, B, C) and need to match them with terms related to chromatography (P, Q, R): - Benzaldehyde: This is typically a molecule or compound which can act as an adsorbate in chromatography. - Alumina: A common stationary phase in chromatography, typically acting as an adsorbent. - Acetonitrile: A solvent often used as a mobile phase in chromatography.

Step 2: Matching the Items

Based on our understanding: - Benzaldehyde corresponds to 'Adsorbate', making (A) match with (R). - Alumina fits the role of 'Adsorbent', corresponding with (Q), making (B) match with (Q). - Acetonitrile is typically a 'Mobile Phase', hence (C) matches with (P).

Step 3: Selecting the Correct Option

From the matches identified, we determine the correct choice among the provided options: - Option (b) has the matches (A) → (R), (B) → (Q), (C) → (P). - This matches the identified pairs correctly.

Key Concepts

Benzaldehyde

Benzaldehyde is a colorless liquid that is commonly used in industries for its almond-like fragrance. In the context of chromatography, it usually functions as an adsorbate. This means it is the substance that will be analyzed and separated during the chromatographic process.
It has a unique chemical structure which includes a formyl group attached to a benzene ring, giving it both its distinct smell and chemical properties that are useful in various applications.
When you run a chromatographic test, benzaldehyde will interact with the adsorbent, creating different separation patterns based on how strongly it adheres to the stationary phase.

• It serves as a key ingredient in the synthesis of other chemicals.
• Its handling requires caution, as it can be irritating to the skin upon contact.

Understanding benzaldehyde's role in chromatography helps in predicting the behavior of similar compounds when subjected to this separation technique.

Alumina

Alumina, also known as aluminum oxide, is a highly porous, white solid material. It is one of the most frequently used substances in chromatography, particularly in column chromatography, where it acts as the adsorbent or stationary phase. This means it supports the solid matrix to which various substances get adsorbed during the separation process.
Alumina is preferred because of its very high resistance to changes in pH and temperature, making it a durable and reliable choice for repeated use.
Its tremendous surface area and high surface energy provide a good anchor for the adsorbate compounds trying to adhere to it.

• Commonly employed in the purification of organic compounds.
• It is essential to activate alumina by heating to enhance its adsorption capacity before use.

Comprehending how alumina interacts with other chromatography components allows better control over the separation conditions and outcome.

Acetonitrile

Acetonitrile is a clear, volatile, and highly polar organic solvent. Known for its effectiveness in various chemical processes, it often serves as a mobile phase in chromatography. The mobile phase is the solvent that moves through the stationary phase, carrying the substances to be separated along with it.
Because of its polar nature, acetonitrile is particularly useful in separating compounds based on their polarity, making it a staple in methods like high-performance liquid chromatography (HPLC).
It is also known for its low viscosity and high elution strength, which contributes to faster and more efficient separation of components.

• Widely used in the pharmaceutical industry for drug analysis.
• Due to its toxicity, handling acetonitrile requires careful attention to safety measures.

Understanding acetonitrile’s characteristics is crucial for optimizing chromatography conditions and achieving precise analytical results.