Medical Chemistry

Medical Chemistry Lecture By: Asst. Led Tariq Al Mgheer - College of Medicine- Babylon University

1.026g, it follows that 500.mLX 1.026 g / mL = 513g
Specific gravity is closely related to density. Specific gravity is the ratio of the density of any material to the density of water at the same temperature. Specific gravity = density of material / density of water
According to this definition, the specific gravity of water is 1.0. Gold has a specific gravity of 19.3. This means that its density is 19.3 times greater than that of water.
Notice that specific gravity is a ratio of two values. The units cancel in this ratio and the value of specific gravity has no units.
The temperature has been given in all calculations because density and specific gravity vary with temperature. The reason for this is that the volume of a sample cnanges with a change in temperature. As a result, the density and specific gravity also change. Such changes are particularly important for liquids and gases. Therefore, comparisons of densities and specific gravities should be made at the same temperature.
Specific gravities of liquids are easilv measured by an instrument called a hydrometer.
Hydrometer can use to measure the specific gravities of battery acid, antifreeze, and urine. In each case, the specific gravity tells us something about the composition of the liquid. For example, a sample of urine from a healthy person has a specific gravity between 1.018 and 1.025 at 25° C. The urine from persons suffering from diabetes contains large quantities of sugar. As a result, the specific gravity of their urine is higher than normal. Thus, the result of taking the specific gravity of a sample of urine, a simple and easy test, serves as a warning of a medical problem.