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Questions and Answers
What is the role of sodium carbonate in the extraction of caffeine?
What is the role of sodium carbonate in the extraction of caffeine?
- React with tannin and gallic acid to form products soluble in dichloromethane (correct)
- React with benzoic acid to form a solid precipitate
- React with caffeine to facilitate extraction
- React with water to remove impurities
What is the purpose of anhydrous sodium sulfate in the extraction process?
What is the purpose of anhydrous sodium sulfate in the extraction process?
- Remove water from the organic layer (correct)
- React with caffeine to form a soluble compound
- React with impurities to make them volatile
- Enhance the solubility of benzoic acid
What is sublimation as described in the text?
What is sublimation as described in the text?
- Transition of a solid into a gas without passing through the liquid stage (correct)
- Transition of a gas into a solid
- Transition of a liquid into a gas
- Transition of a solid into a liquid
Which type of impurity makes substances suitable for purification by sublimation?
Which type of impurity makes substances suitable for purification by sublimation?
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At what temperature does benzoic acid change from a solid to a liquid?
At what temperature does benzoic acid change from a solid to a liquid?
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What distinguishes pure substances from impure substances in terms of melting points?
What distinguishes pure substances from impure substances in terms of melting points?
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Why is benzoic acid commonly used as a food preservative?
Why is benzoic acid commonly used as a food preservative?
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What distinguishes substances suitable for sublimation purification?
What distinguishes substances suitable for sublimation purification?
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Which process involves the conversion of a solid directly into a gas?
Which process involves the conversion of a solid directly into a gas?
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