Ethane (C₂H₆) and ethene (C₂H₄) are both compounds of carbon and hydrogen. Which one is saturated and which i…

Question

Ethane (C₂H₆) and ethene (C₂H₄) are both compounds of carbon and hydrogen. Which one is saturated and which is unsaturated? Give a reason for your answer.

Accepted Answer

## Model Answer **Ethane (C₂H₆) is saturated** and **ethene (C₂H₄) is unsaturated.** In ethane, all valencies of carbon atoms are satisfied by **single bonds** only, so it is saturated. In ethene, the two carbon atoms are joined by a **double bond** (C=C), leaving no free valency — such compounds with double or triple bonds are called unsaturated. *Source: Carbon and its Compounds, Section 4.2.1* --- ## Explanation - Examiners expect you to **name** which is saturated/unsaturated (1 mark) and **give the reason** based on bond type (1 mark). - Key terms to use: *single bond* → saturated; *double/triple bond* → unsaturated. - Avoid vague reasons like "fewer hydrogen atoms" — always refer to the **type of bond** between carbon atoms, as the textbook defines it.

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