AQA · Chemistry · 8462

GCSE Chemistry (AQA): Alcohols

Topic 7 — Organic Chemistry. Generated from the caption track of Cognito's lesson video "GCSE Chemistry - Alcohols"; each card deep-links to the moment in the video it came from. Lesson 7.11 of Cognito's AQA GCSE Chemistry (Triple) course (Higher tier), filed under AQA Chemistry 8462. Teaching by Cognito — https://cognitoedu.org/coursesubtopic/c2-gcse-aqa-h-t_7.11.

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  1. Which functional group defines an alcohol?

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    The -OH (hydroxyl) group, which replaces one of the hydrogens of the corresponding alkane.

  2. Write the balanced equation for the complete combustion of ethanol.

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    C2H5OH + 3O2 → 2CO2 + 3H2O.

  3. Which functional group is present in a carboxylic acid?

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    -COOH.

  4. What are the products of the complete combustion of an alcohol in air?

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    Carbon dioxide and water.

  5. Why are alcohols used as solvents in industry instead of water?

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    They can dissolve substances water cannot, such as hydrocarbons, fats and oils.

  6. Why do the properties of alcohols change along the homologous series?

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    Because the molecules get bigger as chain length increases; the first four are still similar to one another.

  7. How are alcohol names formed from the corresponding alkane names?

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    The final 'e' is replaced with 'ol' — e.g. ethane becomes ethanol.

  8. What is the general formula for the alcohols?

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    CnH2n+1OH — the OH is always written at the end.

  9. Oxidising an alcohol such as ethanol produces a ?.

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    carboxylic acid

  10. Which property of alcohols makes them useful as fuels?

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    They are flammable — they undergo combustion and release a lot of energy, e.g. ethanol in a spirit burner.

  11. What is the pH of an aqueous solution of the first four alcohols?

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    Neutral (pH 7) — alcohols are neither acidic nor alkaline.

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