EXCESS HEAT-CAPACITIES AND EXCESS VOLUMES OF (AN N-ALKYLALKANOATE PLUS HEPTANE OR DECANE OR TOLUENE)

Excess molar heat capacities C(p,m)E at constant pressure have been determined, as a function of mole fraction x at the temperature T = 298.15 K and atmospheric pressure, for eight liquid mixtures: [(1 - x)C6H5CH3 + x{HCO2(CH2)2CH3 or HCO2(CH2)3CH3 or CH3CO2C2H5 or CH3CO2(CH2)2CH3 or CH3CO2(CH2)3CH2)3CH3 or CH3CH2CO2CH3 or CH3CH2CO2C2H5 or CH3CH2CO2(CH2)2CH3}] and four more liquid mixtures: [(1 - x){CH3(CH2)5CH3 or CH3(CH2)8CH3} + x(CH3CO2(CH2)2CH3 or CH3(CH2)2CO2(CH2)2CH3}]. Excess molar volumes V(m)E have been determined, as a function of x at the same temperature and pressure, for the eight mixtures containing C6H5CH3 and for [xCH3CO2(CH2)2CH3 + (1 - x){CH3(CH2)5CH, or CH3(CH2)8CH3}]. The instruments used were a Picker flow microcalorimeter and a vibrating-tube densimeter, respectively. The two mixtures: (propylethanoate + an n-alkane) show positive excess volumes; the mixtures containing C6H5CH3 show either small positive excess molar volumes with V(m)E(x = 0.5)/(cm3.mol-1) = 0.045 {with HCO2(CH2)2CH3} and =0.021 {with HCO2(CH2)3CH3}, or negative excess molar volumes, the more negative being with CH3CH2CO2(CH2)2CH3: V(m)E(x = 0.5)/(cm3.mol-1) = -0.181. The curves of C(p,m)E against x for [(1 - x){CH3(CH2)5CH3 or CH3(CH xCH3CO2(CH2)2CH3] show W-shaped behaviour. C(p,m)E(S) for the mixtures containing C6H5CH3 are rather small, either slightly positive or S-shaped, with a negative part always situated at high mole fractions x of the n-alkanoate.