In gasoline (petrol) formulation, why are antioxidants added to the fuel blend?
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ATo impart a distinctive colour for easy identification
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BTo minimise gum formation by inhibiting oxidation
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CTo prevent carburettor icing in cold weather
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DTo prevent lead build-up in engines
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ETo increase Reid vapour pressure for cold starts
Answer
Correct Answer: To minimise gum formation by inhibiting oxidation
Explanation
Introduction:Gasoline stability is affected by oxidation of unsaturated components, which can form gums and deposits. Antioxidant additives interrupt radical chain reactions responsible for gum formation.
Given Data / Assumptions:
- Fuel: gasoline (petrol).
- Additive: antioxidants (e.g., phenolic or amine types).
Concept / Approach:Antioxidants act as radical scavengers, slowing oxidation that otherwise forms high-molecular-weight gums. This preserves storage stability and protects fuel systems.
Step-by-Step Solution:1) Identify the degradation pathway: oxidation leads to gum formation.2) Match additive function: antioxidants inhibit oxidation chain reactions.3) Conclude purpose: reduce gum formation in service and storage.
Verification / Alternative check:Fuel specifications and additive supplier literature consistently associate antioxidants with improved oxidation stability and reduced gum.
Why Other Options Are Wrong:Colour identification: Dye additives, not antioxidants, impart colour.Prevent icing: Anti-icing agents or alcohols address carburettor icing.Prevent lead build-up: Lead scavengers historically addressed deposits when leaded gasoline was used.Increase RVP: Volatility modifiers, not antioxidants, affect RVP.
Common Pitfalls:Confusing antioxidants with detergents, metal deactivators, dyes, or volatility improvers; each addresses different performance properties.
Final Answer:To minimise gum formation by inhibiting oxidation