A geology student attempts to identify an unknown mineral by measuring its density

CHEMISTRY · Multi-part · CBSE · Chemistry · The Amazing World of Solutes, Solvents, and Solutions · The Amazing World of Solutes, Solvents, and Solutions

Problem

A geology student attempts to identify an unknown mineral by measuring its density. The student records the following data: • Mass of the mineral:

245.0\,\text{g}

measured with a scale that has an uncertainty of

\pm0.5\,\text{g}

. • Volume determination by water displacement: the water level in a graduated cylinder rises from

100.0\,\text{mL}

131.2\,\text{mL}

; each reading has an uncertainty of

\pm0.2\,\text{mL}

. Reference densities at room temperature: Quartz

2.65\,\text{g/cm}^3

Calcite

2.71\,\text{g/cm}^3

Granite

2.75\,\text{g/cm}^3

Basalt

3.0\,\text{g/cm}^3

Galena

7.6\,\text{g/cm}^3

(a) Calculate the density of the mineral and the absolute uncertainty in the density. Show how you propagate the measurement uncertainties. (b) Based on your result from part (a), identify all minerals in the reference list whose tabulated density is consistent with the measured density within the calculated uncertainty. Explain your reasoning clearly. (c) Propose one additional measurement or experimental procedure that could reduce the uncertainty or otherwise help you distinguish among the remaining candidate minerals, and justify how it would improve the identification.

Related theory

Density

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