Question

4. Answer each of the following: (i) Draw the structures and indicate all atoms of both of the following: 1,4 dichloro- 2-pentene, 2-methylpropanol. [4 Marks] (ii) Provide the IUPAC name for each molecule (A-F) below and indicate each functional group present in the molecule. [6x2 Marks] LOH HN B ОН E F The age of wine can be determined by measuring the trace amount of radioactive tritium, the concentration of which diminishes with a half-life of 0.055 year once the wine is bottled. (a) What is the order of the decay process? [3 Marks] (b) What is the half-life for the decay process? [2 marks] (c) If a bottle of wine is found to have a tritium concentration that is 40% that of freshly bottled wine, what is the age of the wine? [4 Marks]

Answer 1

CI CH3 CH CI HO 4. (i) CH H3C CH3 H H2 H2 1,4-dichloro-2-pentene 2-methylpropanol ОН H2N 4. (ii) A IUPAC Name: pentan-2-one Functional group: Ketone(-C=O) B IUPAC Name: ethenamine Functional group: Amine(-NH2) C IUPAC Name: benzoic acid Functional group: Carboxylic acid(-COOH) ОН F E D IUPAC Name: methoxyethane Functional group: Ethar(-OR) IUPAC Name: propan-2-ol Functional group: Alcohol(-OH) IUPAC Name:2-methylpent-2-ene Functional group: Alkene

4. (iii)

(a) The order of the decay process = 1 (First order)

(b) Half life of the decay process(t_1/2) = 0.055 year^-1

(c) The age of the wine = 0.073 year

Rate constant of the decay process, k = 0.693/ t_1/2 = 0.693/(0.055 year-1) = 12.6 year

Concentration of tritium after time t = 40%

Now, age of wine = t year.

So, age of wine = 0.073 years.

2.303 100 t = 2.303 Alo Clogh [4] log 0.0727 year -0.073 year 12.6 year 40

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