Medical Chemistry

Medical Chemistry Lecture By: Asst. Lect. Tariq Al mgherr- College of Medicine- Babylon University
of scale Three scales of temperature are in use today, n the United Stares, temperatures are measured in degrees Fahrenheit (°F). In science, however, the international temperature scales are the Celsius scale and the Kelvin scale.
The Celsius scale abbreviated °C) uses the freezing point of water to define 0° and the boiling point of water as 100°. The scale between these two points is d vided into 100 equal degrees. A comparison between the Celsius and Fahrenheit scales is shown in Figure 1
The Sl unit of temperature is the Kelvin (K). /\ degree is identical on the Kelvin and Celsius scales The only difference between them is that zero is set at different points on the two scales. On the Kelvin scale, zero is the coldest temperature possible, called absolute zero, The zero on the Kelvin scale is equal to -273.15 °C. To convert from the Celsius to the Kelvin scale, simply add 275.15° to the Celsius temperature-
K=°C+273.1i5° or °C=K-273.15
Fig. 1. A comparison of the Fahrenheit and Celsius temperature scales. As shown in Figure 1, there are 180 degrees between the freezing point and the boiling point of water on the Fahrenheit scale, whereas there are only 100 degrees between these two points on the Celsius scale. Therefore, there are 9" F for every 5° C This fact is the origin of the factors 9/5 and 5/9 in the following formulas, which are used to convert degrees Fahrenheit to degrees Celsius and vice versa. °F=9/5 °C+32° and °C = 5/9 (° F - 32°)