Honors Chemistry Richardson
Lab: Measuring the Density of Pennies
1. The equation that relates density, mass, and volume is: density = mass / volume.
2. All substances have unique densities, so if you are able to find the density of a substance, you can properly identify it.
3. We measure irregular-shaped objects with the use of water displacement because it would be nearly impossible to get the exact measurements of items with irregular shaped surfaces manually.
4. It is important to dry a wet object before finding its mass because if you weigh it when it has water on its surface, the extra weight of the water will make the weight measurement invalid.
5. You should tilt a graduated cylinder when you drop in objects because if they drop directly into the water, they might make a splash and displace some of the water, that is measuring the volume of the object, outside of the graduated cylinder.
6. Potassium is the only metal on the table that has a density less than water because water has a density of 1 and Potassium of 0.87.
*Please see attached graphs*
Analysis and Questions:
1. The Pre-1982 Pennies graph line has a slightly higher slope when compared to the Post-1982 Pennies graph. The points on each of the lines appear in about the same area of places on the graph.
2. The values obtained for the slopes of the lines represent the increase of mass and volume in proportion to the number of pennies being used, the slope of the line equals the density of one penny.
3. The density of copper is 8.89, while the density of the Pre-1982 Pennies is 8.17. This means that although the penny's density is close to that of copper, the penny is not all copper, but an alloy made up of different metals, but primarily of copper.
4. The density of the Post-1983 Pennies is 7.11. The metal Zinc is close to having the same density as these pennies because it has a