What is the Freezing Point of Water?
Even though this can sound like a simple question, the answer can be a little bit confusing. Don’t worry, we’re here to help!
Two different things have been known to happen at 32 °F (thirty-two degrees Fahrenheit), or 0 °C (zero degrees Celsius). This is the temperature where water ice will begin to melt. This is known as the “melting point” of water. The melting point of water is a physical property of water. A physical property is used to identify a substance, like water, in this case. That means the melting point is something you can count on happening every time. Water in its solid form, ice, will begin to turn into a liquid.
However, the other thing that has been observed is that when pure liquid water is cooled to 32 °F / 0 °C, ice crystals can begin to form. This was noted a long time ago by a German physicist named Daniel Gabriel Fahrenheit, the inventor of the thermometer and the Fahrenheit temperature scale. So, the term “freezing point” began.
On the other hand, Daniel Fahrenheit also observed that water can remain in its liquid state even below the established freezing point. This is now known as “supercooled liquid.” There are many factors that can influence when a sample of water might actually freeze — such as the water’s mineral content, atmospheric pressure, the size of the water particles, etc. In fact, supercooled water has been observed to remain in a liquid state as low as -94°F / -70°C.
So, how do we answer this question from a practical perspective?
Let’s put it this way. In most cases, 32 °F / 0 °C is the temperature to watch. If you were to leave a bucket of water outside on a cold night when the temperature will reach below 32 °F / 0 °C, there is a high probability that by morning, you will have a bucket of ice.
The Celsius scale was developed by Anders Celsius, a Swedish astronomer, around 1742. It used to be called the “centigrade scale”. Originally, he set 0 °C as the boiling point of water, and 100 °C as the freezing point. It was later switched to what it is today — 0 °C for the freezing point, and 100 °C for the boiling point. The Celsius scale is metric, and is used in most countries throughout the world. The Farenheit scale is used primarily by the United States and its territories.
Water – Physical properties. (n.d.). Encyclopedia Britannica. Retrieved March 4, 2021, from https://www.britannica.com/science/water/Physical-properties
Homogeneous nucleation of supercooled water: Results from a new equation of state. (n.d.). NASA/ADS. Retrieved March 4, 2021, from https://ui.adsabs.harvard.edu/abs/1997JGR…10225269J/abstract
Helmenstine, Ph.D., A. M. (2018, November 30). The Difference Between Celsius and Centigrade Depends on Zero. ThoughtCo. https://www.thoughtco.com/difference-between-celsius-and-centigrade-609226
Zimmermann, K. A. (2013, September 24). Fahrenheit: Facts, History & Conversion Formulas. Livescience.Com. https://www.livescience.com/39916-fahrenheit.html