Mathematical Relationships Between Temperature Scales

Fahrenheit, Celsius, and Kelvin Temperature Scales

Temperature is a fundamental physical property in chemistry, and it can be measured using different scales. The three most common temperature scales in general chemistry are Celsius (°C), Fahrenheit (°F), and Kelvin (K). Understanding how to convert between these scales is essential for laboratory work, calculations, and interpreting scientific data.

Fahrenheit and Celsius

The Celsius scale is based on the freezing and boiling points of water (0°C and 100°C, respectively), while the Fahrenheit scale uses 32°F for the freezing point and 212°F for the boiling point of water. The relationship between these two scales is given by the following equation:

• Conversion from Celsius to Fahrenheit:

• Conversion from Fahrenheit to Celsius:

• Key Point: The Fahrenheit scale has a different zero point and uses a different size for each degree compared to Celsius.

• Example: To convert 25°C to Fahrenheit:

Kelvin and Celsius

The Kelvin scale is the SI unit for temperature and is commonly used in scientific contexts. It starts at absolute zero, the theoretical lowest possible temperature. The size of one Kelvin is equal to one degree Celsius, but the zero point is shifted.

• Conversion from Celsius to Kelvin:

• Conversion from Kelvin to Celsius:

• Key Point: Kelvin temperatures are always positive, and absolute zero (0 K) is equivalent to -273.15°C.

• Example: To convert 100°C to Kelvin:

Summary Table (described): The relationships between temperature scales can be summarized as follows: To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. To convert Celsius to Kelvin, add 273.15. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. To convert Kelvin to Celsius, subtract 273.15.

Additional info: The Kelvin scale is especially important in chemistry because many physical laws and equations (such as the ideal gas law) require temperature to be expressed in Kelvin.