Using the data collected, calculate the density (in g/cm) of your unknown metal.

Question

Using the data collected, calculate the density (in g/cm) of your unknown metal. Show your work clearly, and circle your final result. Your metal could be any of the following metals: lead, aluminum, nickel or zinc. Look up the true densities of these metals and identify your unknown metal. Suggested resources include your text, websites (e.g., www.webelements.com, www.chemicool.com) and the CRC Handbook of Chemistry and Physics. Identity of unknown metal: True density of metal: Source of density data: Calculate the percent error between your experimental density and the true metal density.

Explanation / Answer

Mass of metal (true) =(Mass of metal+Vial) - (mass of vial)=72.6802 g - 22.0343 g=50.6459 g

Mass of metal in water (apparent)=(Mass of metal+vial+water)-(Mass of vial+water)=97.6683 g - 55.5215 g= 42.1468 g

Loss in mass of metal in water= True mass of metal - Apparent mass of metal in water = 50.6459 g - 42.1468 g

=8.4491 g

According to Archimedes' Principle, the apparent loss in weight of an object immersed in a fluid is equal to the weight of the fluid displaced by it.

So mass of water displaced by the metal=8.4491 g

Given density of water at 20 degree celcius= 0.9982 g/cm3

Density=Mass/Volume

So volume of water displaced=Mass of water displaced/Density of water

=8.4491 g/0.9982 g/cm3 = 8.514 cm3

So volume of the metal= 8.514 cm3

(According to Archimedes' principle, for an object fully immersed in a fluid, the volume of the displaced fluid is equal to the volume of the object immersed in the fluid)

Density of Metal=True mass of metal/Volume of metal= 50.6459 g/8.514 cm3 = 5.949 g/cm3

Density of Lead=11.34 g/cm3

Density of Aluminium= 2.70 g/cm3

Density of Nickel= 8.91 g/cm3

Density of Zinc= 7.14 g/cm3

So the metal is closest to Zinc in its density.

Percent error between experimental density and true metal density

Percent error={(Experimental density-True density)/True density}x100

={(5.95-7.14)/7.14}x100=-16.67%

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