In Measuring and Understanding Density, several experiments were performed to find density of regularly shaped objects, irregularly shaped objects, liquids and gasses. An additional experiment was done to find the specific gravity of a sampling of liquids. The purpose of the experiment was to provide a better understanding of density and to be able to extrapolate unknowns based upon these calculations. The experiments yielded data in keeping with Kinetic-molecular theory in regards to the density of water versus its temperature. Key measurements and formulae were also used to determine densities of metal and plastic objects as well as irregularly shaped rocks. It is possible to find the density of an object (be it liquid, gas or solid) by the use of only a select few measurements and the formulae contained herein. Introduction
In observing oil floating on water one unknowingly observes a difference in density. Encyclopedia Britannica describes density as offering “a convenient means of obtaining the mass of a body from its volume or vice versa.” Density calculations are used in a number of ways that impact daily life. They are used in the preparation of ballistics gelatin for testing the actual damage a bullet might do to a human body in order to provide information to forensic scientists (C.J.Shepherd et.al. 2009). Density calculations are also vitally important to ship builders in order to allow them to calculate how much weight a ship with a given sized hull can hold without sinking (Smith, and Jewett 342). Density (d) is relative to mass (m) and volume (V) in as much as d=m/V. This experiment uses this equation in different fashions to analyze certain substances and extrapolate unknown measurements from known measurements. Through the techniques used in this experiment, one can easily determine differing factors about regularly or irregularly shaped materials as well as liquids and gasses, and thereby determine their densities. In knowing the density of an object, further hypotheses can then be made. These hypotheses include which liquids will layer themselves if put in a column relating to density as well as which solids may be heavier or more dense than others. With regard to gasses, one can use the information herein to realize the amount of gas contained within a container and thereby its density. Procedure
In the first of five stages in this experiment, the density of several regularly shaped objects (in g/cm3) was determined. The objects used were: a small metallic rectangle, two small metallic cubes of slightly different size, and two small, solid plastic spheres. The cubes were differentiated by marking them “1” and “2” with a marker. The spheres were dark and so could not be marked but one had a small dent in it and that was used as differentiation. The objects were weighed to a hundredth of a gram on a scale and the mass for each was recorded. In order to obtain a volume for these objects, a formula of length x width x height was used for the rectangle and cubes. In order to obtain the volume of the spheres, a formula of 4/3 pi • r3 was used where r = radius of the sphere. All measurements were done in mm with a ruler and so were converted to cm3 at the end. Once volumes and masses were calculated, they were used in the d = m/V formula to determine densities and these were recorded in g/ml.
In the second stage of this experiment, the density of two irregularly shaped objects was determined. Two small rocks were obtained that differed in size by roughly half. The small rock was labeled rock “A” and the larger was labeled rock “B.” Each rock was weighed on a scale and their masses were recorded. A graduated cylinder was then used that the rocks would fit into and filled with a specific volume of water sufficient to cover the rocks. This volume was recorded and the rocks were then added to the water one at a time with the increase in volume being recorded after each one. This displacement of...
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