Adiabatic and isothermal apparent molal compressibilities of organic compounds in water. I. Cyclic and open-chain secondary alcohols and ethers

The limiting apparent molal adiabatic and isothermal compressibilities in aqueous solutions of alcohols and ethers at various temperatures have been determined by means of ultrasonic velocity measurements. The following compounds have been considered: secondary cyclic and open-chain alcohols (cyclopentanol, cyclohexanol, cycloheptanol, 2-butanol, 3-pentanol, 3-hexanol, 4-heptanol; cyclic ethers of the types (CH₂)₃O_n (n=1, 2, 3), (CH₂)_nO₂ (n=3, 4, 5), and (CH₂)_nO (n=3, 4, 5); and the linear diethers dimethoxymethane, diethoxymethane, and 1,2-dimethoxyethane. The results indicate that both alcohols and ethers cause the water near the solute to become more resistant to pressure than the bulk. This is in agreement with the prediction of a mixture model for water.