Most metals exhibit a specific gravity greater than 1.0.
The specific gravity of a metal represents the ratio of the metal's density to the density of water. Density, in turn, represents the ratio between a substance's mass and volume. Whereas scientists typically state densities in units such as grams per milliliter or kilograms per cubic meter, specific gravity represents a dimensionless quantity. Therefore, irrespective of the units used to measure the metal's density, a calculation of its specific gravity will usually produce the same result.
Instructions
Measurements
1. Weigh the sample of metal on a balance or scale. Feel free to make the measurements in units of grams, ounces or pounds; you will convert the weight to grams in a later step. Write down this value for future reference.
2. Test-fit the metal sample in the graduated cylinder. If the metal sample will not fit into the cylinder, then use a larger cylinder or a measuring cup. The graduated cylinder gives more precise results and should represent your first choice, if suitable.
3. Fill the graduated cylinder or measuring cup approximately half full with water, then place the cylinder or cup on a flat surface and read the volume level from the graduation marks on the container's side. Write down this volume.
4. Lower the metal sample slowly into the water in the cylinder or measuring cup, being careful not to splash or spill the water from the container. With the metal submerged, again place the cylinder or cup on a level surface and read the volume and record this value.
Calculations
5. Determine the volume of the metal sample by subtracting the volume of the water initially in the cylinder or cup from the volume of water after the metal sample was added to the container. For example, an initial volume of 4.2 fluid ounces that increased to 5.7 fluid ounces would represent a metal volume of 5.7 - 4.2 = 1.5 fluid ounces.
6. Convert the mass of the metal sample to grams and the volume of the sample to cubic centimeters using an online conversion tool, such as those provided in the Resources. A metal sample weight of 12.4 ounces, for example, converts to 352 grams (rounded). A metal volume of 1.5 fluid ounces converts to 44 cubic centimeters (rounded).
7. Calculate the density and specific gravity of the metal by dividing its mass in grams by its volume in cubic centimeters. Continuing the previous example, 352 / 44 = 8.0 grams per cubic centimeter. Technically, you should now divide this value by the density of water to determine the specific gravity. However, because the density of water is 1.0 gram per cubic centimeter, this step is unnecessary, that is, the specific gravity and density in units of grams per cubic centimeter are numerically identical. The specific gravity in this case is 8.0.
Tags: metal sample, specific gravity, fluid ounces, cubic centimeter, cubic centimeters
