Specific heats and enthalpies of mixing of amine-H₂O and amine-H₂O-NaCl mixtures

Specific heats of mixtures of dimethylisopropylamine (N,N-dimethyl-2-propanamine) or diisopropylamine (N-(1-methylethyl)-2-propanamine) and water and of dimethylisopropylamine and water saturated with NaCl were measured in a temperature range from 272 to 280 K at atmospheric pressure. The specific heats of the three systems all obtained maximum values in the amine weight fraction range (salt free) of 0.1 to 0.4. The enthalpies of mixing of dimethylisopropylamine or diisopropylamine and water were determined as a function of the amine concentration in the mixture. The mixing of water and the amines was strongly exothermic. The highest measured enthalpies of mixing per gram of mixture were -105 J·g^-1 for dimethylisopropylamine-H₂O at an amine weight fraction of 0.49 and -81 J·g^-1 for diisopropylamine-H₂O at an amine weight fraction of 0.60.