To determine the specific gravity of a substance based on its density, you must compare it to the density of a reference substance, typically water.

 To determine the specific gravity (SG) of a substance, you follow a simple formula:

\[ SG = \frac{\text{Density of the substance}}{\text{Density of the reference substance (water)}} \]

Since the density of water is \(1 \text{ g/cm}^3\) at 4°C (or \(1000 \text{ kg/m}^3\)), you can usually just divide the density of your substance (in the same units) by this value. Here are the steps you would take:

1. Measure the density of the substance. This is usually in grams per cubic centimeter (\(g/cm^3\)) or kilograms per cubic meter (\(kg/m^3\)). 2. Divide the density of your substance by the density of water. If you're using \(g/cm^3\), the density of water is \(1 g/cm^3\); if you're using \(kg/m^3\), it's \(1000 kg/m^3\).

3. The result is the specific gravity, a dimensionless number (since you're dividing two densities with the same units, they cancel out).

For example, if a substance has a density of \(2.5 g/cm^3\), its specific gravity would be:

\[ SG = \frac{2.5 g/cm^3}{1 g/cm^3} = 2.5 \]

This means the substance is 2.5 times as dense as water.