Melting and Boiling Points of Acetone: Key Facts and Influencing Factors

If you work with solvents, you’ll know that acetone stands out for its low boiling point and extreme cold resistance. Under normal atmospheric pressure, it boils at 56.5°C (133.7°F) and freezes at around -95°C (-139°F). These figures are not just textbook data—they explain why acetone evaporates so quickly on your skin, why it’s ideal for certain manufacturing processes, and why it can remain liquid even in very low-temperature environments.

Acetone in Brief

Acetone (C₃H₆O) is a transparent, volatile liquid with a faintly sweet odor. It mixes easily with water and most organic solvents, which is why it’s widely used in cleaning, degreasing, and as a base for many cosmetics. Its chemical structure makes it especially effective at breaking down oils, resins, and certain polymers.

Boiling Point Explained

At 56.5°C under 1 atm pressure, acetone’s vapor pressure matches the surrounding air pressure, causing it to rapidly change from liquid to gas. This relatively low boiling point means it evaporates quickly—an advantage in applications where rapid drying is needed, such as surface preparation before painting or in certain adhesive processes.

Melting Point Details

Acetone freezes at approximately -95°C. This low melting point reflects its weak intermolecular forces, which allow the molecules to stay in liquid form at temperatures far below freezing. This property makes it valuable for cold-weather or cryogenic processes where other solvents would solidify.

Key Factors That Influence These Temperatures

Applications Where These Properties Matter

• Industrial: Used for cleaning and degreasing metal parts; quick evaporation shortens processing times.
• Laboratory: Favored in chromatography and sample preparation due to its volatility and miscibility.
• Consumer: Common in nail polish removers, paint thinners, and household cleaners.
• Low-Temperature Work: Remains liquid in extreme cold, useful for certain cryogenic applications.

Safe Handling Notes

Acetone is highly flammable, with a flash point of -20°C (-4°F). According to the U.S. National Institute for Occupational Safety and Health (NIOSH), it should be used in well-ventilated spaces and stored away from heat sources. Avoid prolonged skin contact to prevent irritation.

Summary

In short, acetone’s melting point of about -95°C and boiling point of 56.5°C define much of its practical value. They explain its speed of evaporation, stability in cold conditions, and suitability across industries—from manufacturing to cosmetics. Knowing these properties is essential for using acetone effectively and safely.