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S6 Chemistry: Organic Reactions and Isomerism (Paper 1: basics)
S6 Chemistry: Organic Reactions and Isomerism (Paper 1: basics)
Ten basics items on the number of structural isomers of butane, relative molecular mass, oxygen needed for propene, the bromine water test, hydration of ethene, mass from addition polymerisation, ethanol from fermentation, volume from cracking, and the idea of isomerism.
Direct answers Answers in order: two, 58.0, 4.5 mol, 90.0 cm3, the colour fades, ethanol, 14.0 g, 46.0 g, 2.40 dm3, and not necessarily, they may be isomers.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S6 Chemistry: Organic Reactions and Isomerism |
| Level | S6 |
02 Questions (10 items)
- FoundationHow many structural isomers does butane C4H10 have?
- FoundationCalculate the relative molecular mass of butane C4H10 with C as 12.0 and H as 1.0.
- FoundationHow many moles of oxygen are needed for the complete combustion of 1 mol of propene C3H6?
- IntermediateWhat volume of oxygen at the same temperature and pressure reacts with 20.0 cm3 of propene?
- IntermediateWhat is seen when ethene is bubbled through bromine water?
- IntermediateWhat forms when ethene reacts with steam over a phosphoric acid catalyst?
- ChallengeWhat mass of poly(ethene) forms when 0.50 mol of ethene polymerises by addition?
- ChallengeWhat mass of ethanol can be obtained from 0.50 mol of glucose by fermentation?
- ChallengeDecane cracks into octane and ethene. What volume of ethene at 24.0 dm3 per mol comes from 0.10 mol of decane?
- Error redoMust two substances with the same molecular formula be the same compound? Why?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Two: butane and 2-methylpropane | The molecular formula is the same but the atoms are joined differently, so the two are structural isomers. |
| 2 | 58.0 | Four carbons give 48.0 and ten hydrogens add 10.0, so the total is 58.0. |
| 3 | 4.5 mol | The equation is C3H6 plus 4.5 O2 giving 3 CO2 and 3 H2O, so the coefficient of oxygen is 4.5. |
| 4 | 90.0 cm3 | Gas volumes follow the mole ratio, so 20.0 times 4.5 gives 90.0 cm3. |
| 5 | The orange brown colour fades to colourless | Ethene adds bromine in an addition reaction, so the bromine is used up and the colour disappears. |
| 6 | Ethanol | This is the industrial hydration of ethene: C2H4 plus H2O gives C2H5OH. |
| 7 | 14.0 g | Addition polymerisation loses no atoms, so the mass is 0.50 times 28.0, that is 14.0 g. |
| 8 | 46.0 g | One glucose gives two ethanol, so 0.50 mol of glucose gives 1.00 mol of ethanol, that is 46.0 g. |
| 9 | 2.40 dm3 | The equation is C10H22 giving C8H18 plus C2H4 in a one to one ratio, so 0.10 times 24.0 gives 2.40 dm3. |
| 10 | Not necessarily, they may be isomers of each other | A molecular formula counts atoms only, and a different arrangement of the same atoms gives isomers with different properties. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Write the molecular formula and functional group first, decide the reaction type, then do the mole calculation.Tutor Registration →
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