Aniline point interpretation: A high aniline point measured for a petrodiesel sample most strongly indicates which compositional character?
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AIt is highly aromatic in nature.
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BIt is highly paraffinic in nature.
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CIt has a very low diesel index.
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DIts ignition quality is very poor.
Answer
Correct Answer: It is highly paraffinic in nature.
Explanation
Introduction / Context:Aniline point is the minimum temperature at which equal volumes of aniline and a petroleum fraction are completely miscible. It is widely used as a qualitative indicator of aromaticity versus paraffinity.
Given Data / Assumptions:
- Measured property: aniline point, relatively high value.
- Sample: diesel-range fuel.
- Interpretation sought: what composition does a high aniline point suggest?
Concept / Approach:Aromatics are more soluble in aniline than paraffins. Therefore, higher aromatic content depresses the aniline point, while higher paraffinic content elevates it. A high aniline point thus indicates a paraffinic character.
Step-by-Step Solution:
Step 1: Recall: high aniline point ↔ low aromaticity ↔ high paraffinity.Step 2: Map this directly to the diesel sample’s composition.Step 3: Choose the option indicating “highly paraffinic in nature.”Verification / Alternative check:Correlations between aniline point, diesel index, and smoke point show that paraffinic fuels tend to have higher aniline points and better smokeless burning behavior.
Why Other Options Are Wrong:
- Highly aromatic: Would correspond to a low aniline point.
- Very low diesel index / very poor ignition quality: Diesel index often rises with paraffinity; the statements do not follow from a high aniline point.
Common Pitfalls:Assuming aniline point gives a quantitative aromatic percentage; it is qualitative and comparative.
Final Answer:It is highly paraffinic in nature.