Appendix 2 Sample Laboratory Write Up Please note that this is only a sample and does not refer to an actual experiment or actual data The scenario in this case is that New England Chemical Solutions Inc NECSI has performed an analysis of some coins purchased by the client Col Lector at a yard sale To From Date Re Col Lector S Marty Pants NECSI Investigator August 22 2009 Gold Coin Analysis On behalf of my colleagues at NECSI I am pleased to report to you the results of our investigation on the gold coins that you submitted for examination Fellow investigator Stu Dent and I performed an analysis of the coins and conclude regretfully that they are not composed of solid gold Our analysis involved the determination of the densities for the coins as well as for a standard sample of gold Density is calculated as the mass divided by the volume Density is a unique property for a given metal including gold which has a distinctively larger density than all other metals usually used to make coins We obtained the masses of all samples on laboratory balances and then determined the volumes via the displacement of water in a small graduated cylinder Because both coins had identical densities within experimental error we assume that they are both composed of the same material We compared the densities of your coins with those of our gold standard Our data are shown as Table 1 attachment on page 2 which also contains literature values for the densities of relevant metals The average value for the density of the coins was determined to be 7 10 g cm3 with a standard deviation 0 311 and a relative standard deviation of 4 3 Our techniques appear to be within a reasonable degree of error about 5 We attribute apparent density differences between the coins largely to the error in reading the volumes on the graduated cylinders which were difficult to read by eye closer than to the nearest 0 1 mL Our balances naturally provide a very small degree of error as well In addition there are also some slight discolorations on the surface of the coins indicating that the coins are not 100 pure These discolorations are most likely due to the oxidation of the metal s making up those coins or to substances adhering to the coins from handling We are quite confident of the overall result that the coins are not solid gold because their densities are clearly different than the literature value for gold 19 300 g cm3 1 Moreover the same experimental techniques used for your coins yielded a density for the gold standard that was within 1 2 of the literature value We find that actually the literature value for the density of zinc 7 140 g cm3 2 is only about 1 different than that of your coins which is well within the expected magnitude of experimental error suggesting the possibility that your coins may actually be composed of zinc with a thin coating of a golden substance or are made of a zinc alloy some of which can appear golden in color We recommend that you take your coins to an authorized professional coin dealer for appraisal as they are interesting in their own right despite not being made of gold as you had hoped We thank you for your business and hope that you think of us again should the need arise Sample CH142 report page 2 of 2 Table 1 Experimental data for density measurements of unknown coins Sample Unknown coin 1 Unknown coin 2 Gold standard Literature Gold Literature Zinc Mass g 6 589 6 881 47 651 1 Volume cm3 0 900 1 000 2 50 Density g cm3 7 32 6 88 19 06 19 3001 7 1402 http www webelements com webelements elements text Au phys html 2 http www webelements com webelements elements text Zn phys html