Question

If glycerine (C₃H₈O₃) and methyl alcohol (CH₃OH) are sold at the same price per kg, which would be cheaper for preparing an antifreeze for the radiator of a car?

Answer 1

The freezing point is lowered when one mole of various compounds is dissolved separately in the same volume of a solvent. Since methyl alcohol (32 g mol⁻¹) has a substantially lower molecular mass than glycerine (92 g mol⁻¹), using it would be less expensive because a given mass of methyl alcohol would contain more moles. Therefore, less methyl alcohol would be required to obtain a specific value of ΔT_f.