Temperature conversions are an essential part of science, engineering, and daily life, especially when dealing with historical or less commonly used scales. While Celsius (°C) and Fahrenheit (°F) are widely recognized today, the Réaumur scale (°Re) still holds importance in specific scientific contexts, food industries (like cheese and sugar making), and historical studies. In this article, we will explain how to convert 19.81 °C into Réaumur step by step, provide the conversion formula, and give you a clear example for better understanding.
🔹 Réaumur Scale
The Réaumur scale was introduced in 1730 by René Antoine Ferchault de Réaumur, a French scientist.
- The scale defines the freezing point of water at 0°Re and the boiling point of water at 80°Re.
- This makes the scale directly proportional to Celsius but compressed, as it uses only 80 divisions between freezing and boiling compared to Celsius’s 100 divisions.
Thus, the Réaumur scale is smaller than the Celsius scale by a ratio of 4:5.
🔹 Formula: Celsius to Réaumur Conversion
The direct conversion formula is: °Re=°C×45°Re = °C \times \frac{4}{5}°Re=°C×54
Where:
- °Re = Temperature in Réaumur
- °C = Temperature in Celsius
This means every 1°C equals 0.8°Re.
🔹 Step-by-Step Conversion of 19.81 °C to Réaumur
Now, let’s apply the formula to convert 19.81 degrees Celsius into Réaumur: °Re=19.81×45°Re = 19.81 \times \frac{4}{5}°Re=19.81×54 °Re=19.81×0.8°Re = 19.81 \times 0.8°Re=19.81×0.8 °Re=15.848°Re = 15.848°Re=15.848
✅ Therefore, 19.81 °C is equal to approximately 15.85 °Re (rounded to two decimal places).
🔹 Why is This Conversion Useful?
- Food Industry – Some traditional European recipes, like cheese fermentation or sugar boiling, still refer to the Réaumur scale.
- Historical Research – Many old scientific documents and weather records were documented in °Re.
- Educational Purposes – Understanding how scales interrelate helps students strengthen their grasp of thermodynamics.
🔹 Celsius to Réaumur Quick Reference Table
Here’s a small conversion chart to give you a better perspective:
| Celsius (°C) | Réaumur (°Re) |
|---|---|
| 0 °C | 0 °Re |
| 10 °C | 8 °Re |
| 20 °C | 16 °Re |
| 25 °C | 20 °Re |
| 50 °C | 40 °Re |
| 100 °C | 80 °Re |
From this table, you can see the proportional relationship clearly.
🔹 Key Takeaways
- The conversion formula from Celsius to Réaumur is: °Re=°C×45°Re = °C \times \frac{4}{5}°Re=°C×54
- For the given example, 19.81 °C = 15.85 °Re.
- The Réaumur scale is mainly of historical and industrial importance today but still appears in certain contexts.
🔹 Final Words
Understanding temperature conversions is crucial for accuracy in science, history, and culinary arts. With the simple ratio of 4:5, converting Celsius to Réaumur is straightforward. For instance, 19.81 degrees Celsius equals 15.85 degrees Réaumur, proving how useful and simple the process can be once you know the formula.
Whether you’re a student, a researcher, or someone passionate about traditional methods, having clarity about such conversions broadens your knowledge and helps in practical applications.