User
Scientific Background
A coin collector has recently purchased three Leif Ericson silver dollars from a website. After receiving the coins, the collector begins to suspect that the coins are not identical, and therefore, one or more of them is counterfeit or fake. The collector has submitted the coins to a laboratory to confirm their identities as either authentic and made of silver or counterfeit and made of aluminum.



Writing Task
Write a report for the coin collector that analyzes the obtained data on the three coins and explains how the data confirms the identity of each coin.


In your essay, be sure to complete the following tasks:
- Calculate the density of the three coins using the data provided in Document D. Explain the results of the calculations, including how the density can be used to identify a substance.
- Identify the likely composition of each of the three Leif Ericson coins from the flame test data. Explain how the flame test can be used to confirm the identity of a metal.
- Justify your identification of the identity of each coin using the chemical reaction test data.

Using document A,B and C



DOCUMENT A
Density of suspected metals
Element Density (grams per cubic centimeter)
Silver 10.5
Aluminum 2.7


DOCUMENT B
Chemical reaction test results
Object
Reaction with sulfuric acid (H2SO4)
Control - Pure Silver Coin Reaction to form a white precipitate
Control - Pure Aluminum Coin Reaction to form a grey solution
Leif Ericson Coin 1 Reaction to form a white precipitate
Leif Ericson Coin 2 Reaction to form a white precipitate
Leif Ericson Coin 3 Reaction to form a grey solution


DOCUMENT C
Flame test results
Object Change in flame color
Control - Pure Silver Coin No change
Control - Pure Aluminum Coin Silver-white
Leif Ericson Coin 1 No change
Leif Ericson Coin 2 No change
Leif Ericson Coin 3 Silver-white

Document D
Physical measurements of the Leif Ericson coins
Coin Mass (g) Volume (cm3)
Leif Ericson Coin 1 26.2 2.51
Leif Ericson Coin 2 25.9 2.49
Leif Ericson Coin 3 7.5 2.77