CBSE Class 10 Answered

An antifreeze is a chemical additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments and also achieves boiling-point elevation ("anti-boil") to allow higher coolant temperature. Freezing and boiling points are colligative properties of a solution, which depend on the concentration of the dissolved substance. Methanol has freezing point at around -98^oC so it can make the liquid substance not to freeze easily after adding methanol into it.

 

Ethylene glycol has desirable thermal properties, including a high boiling point, very low freezing point, stability over a wide range of temperatures, and high specific heat and thermal conductivity and has a very low volatility compared to methanol and to water. Hence it is used an antifreezing agent.