The structure of vitamin C is shown in Fig. 4.1. [Figure 4.1]

1. (a)Deduce the empirical formula of vitamin C.[1]
2. (b)(i)A vitamin C tablet is dissolved in water to produce 200.0 cm³ of vitamin C solution. 5.00 cm³ of this vitamin C solution is added to a flask with approximately 150cm³ of water and an indicator. Exactly 28.40 cm³ of 5.00 × 10–4 mol dm-3 I2(aq) reacts with the sample of vitamin C solution in the flask. [Mr: vitamin C, 176] Calculate the amount, in mol, of I2(aq) added to the flask in this titration. [Figure 4.2][1]
3. (b)(ii)Use your answer to (b)(i) to calculate the mass, in g, of vitamin C in the tablet. Show your working. (If you were unable to calculate a value for the amount of I2(aq) in (b)(i), use the value 2.64 x 10-4 mol. This is not the correct value.)[2]
4. (b)(iii)Deduce the role of I2(aq) in the reaction in Fig. 4.2.[1]
5. (b)(iv)Suggest two reasons why hot concentrated acidified potassium manganate(VII) is not a suitable reagent for producing Q from vitamin C.[2]
6. (c)Predict two absorptions that will be seen in the infrared spectra of both vitamin C and Q. Describe the relevant bond and the specific functional group that is responsible for each absorption identified. [Figure 4.3] Table 4.1 bond functional groups containing the bond characteristic infrared absorption range (in wavenumbers)/cm-1 C-O hydroxy, ester 1040-1300 C=C aromatic compound, alkene 1500-1680 C=O amide carbonyl, carboxyl ester 1640-1690 1670-1740 1710-1750 C≡N nitrile 2200-2250 C-H alkane 2850-2950 N-H amine, amide 3300-3500 O-H carboxyl hydroxy 2500-3000 3200-3650 [2]

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