ACJC_H2_CHEM_P3 Prelim

2 Answer any four questions. (ii) ergie given alculate the enthalpy change for the above reaction. [2] Bond Energies /kJ mol-1 1 Penicillin can be made in the laboratory by reacting 6-aminopenicilanic acid with a suitable acyl chloride. For a particular penicillin, the acyl chloride is the CH3CH2CH=CHCH2COCl. Since the acyl chloride used can be easily made from the corresponding carboxylic acid, the chemist has decided to work with CH3CH2CH=CHCH2CO2H because the acyl chloride is more reactive. (a) (i) The acyl chloride, CH 3CH2CH=CHCH2COCl, can be obtained by reacting CH3CH2CH=CHCH2CO2H with PCl5. Write a balanced equation for the reaction. [1] Using relevant data from the Data Booklet and the bond en s below, c P-Cl P=O 423 322 The carboxylic acid, CH(b) (i) e reaction. [1] (ii) romine. Name and describe the mechanism involved. [4] (iii) in wh ch the hydroxyacid obtained istinguished from its starting material. [2] (c) (i) r w etected. Draw the structure of this ester. Circle the chiral centre(s). [2] (ii) tate the number of sp 2 and sp3 hybridised carbons in the ester. [2] (iii) e re gent nd condition onversion and draw the structure of this diol. [2] (d) (i) including state symb ls for the com f the diol under standard condition. [1] (ii) eriment to etermine the mass of diol used. The following results were obtained. 0 g emperature rise = 44 oC sults give above calcu nthalpy change for the combustion of the diol. [3] [Total: 20] 3CH2CH=CHCH2COOH, can be converted into the hydroxyacid, CH3CH2CH(OH)CH2CH2COOH. Give the reagent and condition for th The hydroxyacid obtained can be distinguished from its starting material by using b Suggest another reagent and condition i can be d In the course of preparing the hydroxyacid, an internal chiral este as also d S This ester may be made into a diol. Give th a a for the c An experiment was carried out to determine the enthalpy change of combustion of this diol. Write a balanced equation o bustion o A large beaker of water was placed on the stove and heated. The temperature rise was recorded. The cylinder was weighed before and after the exp d Mass of diol used = 3.4 g Mass of water heated = 50 T Using relevant data from the Data Book let and r e n , late the e © ACJC 2009 9746/03/Prelim/09 [Turn over

3 [2] (b) tionalize the relative stability of CsI and LiI . [3] (c) (i) values from the Data Booklet, calculate the enthalpy [2] Ca(s) + Ca2+(g)  2Ca+(g) (ii) u onclud about the relative stability of Ca +(g th r spect nd Ca2+? [1] (d) tions between the aqueous ions of Ca and the solid Ca metal is iven as follows: Ca(s) + Ca2+(aq)  2Ca+(aq) ΔH = +63 kJ mol-1 the light of you