Density is one of the basic properties of matter. Density is defined as the mass of an object divided by the volume of the object. This yields a density of mass per unit volume. If 2 objects have the same volume, but different densities, the object with the higher density will weigh more than the identical looking object having the lower density. While the densities of some objects can be modified by outside pressure, particularly gases, the density of metals is the same under any condition. Knowing the density of an object can be a valuable tool in determining the make up of a sample of unknown material, as no 2 metals have the same density. Use these tips to learn how to measure the density of metals.
1Weigh the object. Use any accurate weighing technique, such as a pan balance, to measure the weight of the object. Weigh the object while it is dry so that absorbed water does not affect the accuracy of the weighing.Ad
2Determine the volume of the object by measurement. Measurements can be done if the object is regularly shaped and uniform.
- Measure the object. Use the vernier calipers to measure the dimensions of regularly shaped and uniform objects. With the shape and dimensions of the object known, basic mathematical calculations will yield the volume. For example, the volume of a regular rod is length times pi times radius squared, while the volume of a rectangle is the product of length width and depth.
3Find the volume of the object by displacement. Displacement will be required to find the volume of an irregularly shaped object that cannot be accurately measured. For example, a piece of rock gathered by a geologist would be too irregular to measure and it's volume would have to be found by displacement.
- Prepare the displacement measuring vessel. Put a beaker of water on the pan weighing balance. Make sure that there is enough water in the beaker to cover the object to be measured. Do not overfill the beaker to the point where introduction of the object to the baker would cause the water to overflow and spill out of the beaker, which would ruin the measurement.
- Record the water level in the beaker.
- Test the object. Tie the object to the end of a light string and lower the object in to the water such that it is fully submerged. Record the new water level in the beaker.
- Calculate the apparent volume change in the beaker. Multiply the increase in water level by the surface area of the water to obtain the volume added to the beaker by the introduction of the object. This added volume is the volume of the object.
4Calculate density. Divide the weight of the object by the volume of the object. The result of this division is the density of the object.Ad
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Things You'll Need
- Pan weighing balance
- Vernier calipers
Sources and Citations
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