Question

State the freezing point of water on the following temperature scales: (a) Fahrenheit (b) Celsius (c) Kelvin

Short answer

Water freezes at 0°C, 32°F, and 273.15 K.

Step-by-step solution

Freezing Point in Celsius

The freezing point of water in the Celsius scale is the temperature at which water transitions from liquid to solid. By definition, this occurs at 0°C.

Freezing Point in Fahrenheit

The Fahrenheit scale uses a different scale and reference points. On this scale, water freezes at 32°F. This can be calculated using the formula that converts Celsius to Fahrenheit: \[ F = C \times \frac{9}{5} + 32 \] Plugging in the freezing point in Celsius (0°C), we have:\[ F = 0 \times \frac{9}{5} + 32 = 32°F \]

Freezing Point in Kelvin

The Kelvin scale starts at absolute zero and uses the same increment as the Celsius scale. To convert from Celsius to Kelvin, use the formula: \[ K = C + 273.15 \] Therefore, the freezing point of water in Kelvin is:\[ K = 0 + 273.15 = 273.15 \, K \]

Key concepts

Freezing Point

The freezing point of a substance is the temperature where it changes from a liquid to a solid. For water, this is particularly important in various scientific and everyday contexts. Understanding the freezing point is crucial in weather predictions, cooking, and preserving. In scientific terms, the freezing point of water is where the molecular motion slows down enough to form a crystalline structure.

Different temperature scales may be used to express this transition, depending on the region and the field of study. Knowing the freezing point across these scales is essential for accurate data communication. We explore how the freezing point of water is represented in the Celsius, Fahrenheit, and Kelvin scales below.

Celsius Scale

The Celsius scale is perhaps the most intuitive when thinking about freezing and boiling points of water. This temperature scale is part of the metric system and is used globally by scientists and the general public. The scale is based upon the freezing and boiling points of water under normal atmospheric pressure.

• The freezing point in Celsius: 0°C
• Named after Anders Celsius, a Swedish astronomer

The scale sets the freezing point of water at 0°C and the boiling point at 100°C. It is particularly user-friendly in daily life and aligns closely with human-oriented thermal comfort ranges. This simplicity is why Celsius is taught early in science education.

Fahrenheit Scale

When it comes to the Fahrenheit scale, it is most commonly used in the United States. The scale was developed by Daniel Gabriel Fahrenheit in the early 18th century. Unlike Celsius, the Fahrenheit scale places the freezing point of water at 32°F.

• Freezing point in Fahrenheit: 32°F
• Equation for conversion: \( F = C \times \frac{9}{5} + 32 \)

This formula means you can easily convert Celsius to Fahrenheit, often useful in scientific calculations and international travels. Despite being less intuitive for scientific work due to its non-round numbers at key intervals, it remains popular in the US.

Kelvin Scale

The Kelvin scale is the SI unit of temperature and is widely used in scientific research. What makes the Kelvin scale unique is that it starts at absolute zero, the coldest possible temperature where molecular motion stops.

• Freezing point in Kelvin: 273.15 K
• Formula for conversion: \( K = C + 273.15 \)

Scientists prefer the Kelvin scale because it directly relates to the energy of molecules. Since there are no negative temperatures in this scale, it is particularly useful when dealing with thermodynamic calculations. The freezing point in Kelvin shows how it aligns with the natural properties of water and offers more precision, crucial in physics and chemistry.