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S6 Chemistry: Organic Reactions and Isomerism (Paper 4: misconception drill)
S6 Chemistry: Organic Reactions and Isomerism (Paper 4: misconception drill)
Ten drill items on the alkane formula, butane isomers, the mass of ethanoic acid, the product of hydrogen bromide addition, percentage carbon in ethene, the mass of ethene, oxygen for propene and ethanol, the reversibility of esterification, and isomers against boiling point.
Direct answers Answers in order: CnH2n+2, two, 60.0, 109.0, 85.7 percent, 7.0 g, 4.5 mol, 3 mol, a reversible reaction, and different shapes give different forces and boiling points.
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)
- FoundationWhat is the general formula of the alkanes?
- FoundationHow many structural isomers does butane C4H10 have?
- FoundationWhat is the relative molecular mass of ethanoic acid?
- IntermediateWhat is the relative molecular mass of the product of ethene and hydrogen bromide?
- IntermediateWhat percentage by mass of ethene is carbon?
- IntermediateWhat is the mass of 0.25 mol of ethene?
- ChallengeHow many moles of oxygen does 1 mol of propene need for complete combustion?
- ChallengeHow many moles of oxygen does 1 mol of ethanol need for complete combustion?
- ChallengeWhy can esterification never reach 100 percent yield?
- Error redoA student thinks compounds with the same molecular formula must have the same boiling point. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | CnH2n+2 | Alkenes are CnH2n and the two are often confused, so remember that an alkane has two more hydrogens. |
| 2 | Two | Only one branched form exists, 2-methylpropane, so with straight chain butane there are two. |
| 3 | 60.0 | CH3COOH is C2H4O2, so 24.0 plus 4.0 plus 32.0 gives 60.0. |
| 4 | 109.0, bromoethane | For C2H5Br the parts are 24.0, 5.0 and 80.0, giving 109.0. |
| 5 | 85.7 percent | 24.0 divided by 28.0 and multiplied by 100 gives 85.7 percent. |
| 6 | 7.0 g | 0.25 times 28.0 gives 7.0 g. |
| 7 | 4.5 mol | The equation is C3H6 plus 4.5 O2 giving 3 CO2 and 3 H2O. |
| 8 | 3 mol | The equation is C2H5OH plus 3 O2 giving 2 CO2 and 3 H2O. |
| 9 | The reaction is reversible and hydrolysis runs at the same time | Unless the water is removed, the reverse reaction turns the ester back into the alcohol and the acid. |
| 10 | Isomers share a formula but differ in shape, so the forces between molecules differ and the boiling points can differ by several degrees | Boiling depends on intermolecular forces, and a more branched isomer has less contact area and a lower boiling point. |
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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