Which would be the best reagent to use to determine whether an unknown substance was 2-methylpropan-1-ol or 2-methylpropan-2-ol?
- Bromine water
- Potassium nitrate solution
- Sodium carbonate solution
- Acidified potassium permanganate solution
CHEMISTRY, M7 2020 HSC 29
| The flow chart shows reactions involving five different organic compounds, |  |
to |  |
| Draw the structure of each compound | |
to | |
in the corresponding space provided. (5 marks) |
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CHEMISTRY, M8 2022 HSC 27
A bottle labelled 'propanol' contains one of two isomers of propanol.
- Draw the TWO isomers of propanol. (2 marks)
- Describe how
spectroscopy might be used to identify which isomer is in the bottle. (2 marks)
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- Each isomer produces a different product when oxidised.
- Write equations to represent the oxidation reactions of the two isomers. Include reaction conditions. (3 marks)
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a. Isomer 1:
Isomer 2:
b. Identifying isomers with
→ this can be used to identify the isomers in the bottle because they show a different number of signals which helps deduce the carbon environment.
→ Propan-1-ol contains 3
c.
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a. Isomer 1:
Isomer 2:
b. Identifying isomers with
→ this can be used to identify the isomers in the bottle because they show a different number of signals which helps deduce the carbon environment.
→ Propan-1-ol contains 3
c.
♦ Mean mark (c) 52%.
CHEMISTRY, M6 2021 HSC 35
A manufacturer requires that its product contains at least 85% v/v ethanol.
The concentration of ethanol in water can be determined by a back titration. Ethanol is first oxidised to ethanoic acid using an excess of acidified potassium dichromate solution.
The remaining dichromate ions are reacted with excess iodide ions to produce iodine
The iodine produced is then titrated with sodium thiosulfate
A 25.0 mL sample of the manufacturer's product was diluted with distilled water to 1.00 L. A 25.0 mL aliquot of the diluted solution was added to 20.0 mL of 0.500 mol L¯1 acidified potassium dichromate solution in a conical flask. Potassium iodide (5.0 g) was added and the solution titrated with 0.900 mol L¯1 sodium thiosulfate. This was repeated three times.
The following results were obtained.
The density of ethanol is 0.789 g mL¯1.
Does the sample meet the manufacturer's requirements? Support your answer with calculations. (7 marks)
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CHEMISTRY, M7 2021 HSC 26
A sequence of chemical reactions, starting with 2-methylprop-1-ene, is shown in the flow chart.
- Complete the flow chart by drawing structural formulae for compounds
, , , and . (4 marks)
- Reflux is used in the synthesis of methyl 2-methylpropanoate.
- Provide TWO reasons for using this technique. (2 marks)
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a. Compound A:
Compound B:
Compound C:
Compound D:
b. Reasons for reflux technique:
→ Reflux heats the reaction mixture which increases the average kinetic energy, and thus increases the reaction rate.
→ Heating causes the volatile substances to form vapour molecules. Refluxing uses a condenser to cool the vapour molecules into liquids, and thus retains the substances.
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a. Compound A:
Compound B:
Compound C:
Compound D:
b. Reasons for reflux technique:
→ Reflux heats the reaction mixture which increases the average kinetic energy, and thus increases the reaction rate.
→ Heating causes the volatile substances to form vapour molecules. Refluxing uses a condenser to cool the vapour molecules into liquids, and thus retains the substances.
♦ Mean mark (b) 46%.
CHEMISTRY, M7 2021 HSC 13 MC
A chemist synthesises a substance using the following pathway.
What are compounds
