Calculating the Density of an Ionic SolidRubidium iodide

Chapter , Problem 1PE

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Calculating the Density of an Ionic Solid

Rubidium iodide crystallizes with the same structure as sodium chloride. (a) How many iodide ions are there per unit cell? (b) How many rubidium ions are there per unit cell? (c) Use the ionic radii and molar masses of \(\mathrm{Rb}^{+}\left(1.66\ \AA, 85.47 \mathrm{~g} / \mathrm{mol}\right)\) and \(\mathrm{I}^{-}(2.06\ \AA, 126.90 \mathrm{~g} / \mathrm{mol})\) to estimate the density of rubidium iodide in \(\mathrm{g} / \mathrm{cm}^{3}\).

Given the ionic radii and molar masses of \(\mathrm{Sc}^{3+}(0.88\ \AA, 45.0 \mathrm{~g} / \mathrm{mol})\) and \(\mathrm{F}^{-}(1.19\ \AA, 19.0 \mathrm{~g} / \mathrm{mol})\) what value do you estimate for the density of \(\mathrm{ScF}_{3}\), whose structure is shown in Figure 12.27? (a) \(5.99 \mathrm{~g} / \mathrm{cm}^{3}\), (b) \(1.44 \times 10^{24} \mathrm{~g} / \mathrm{mol}\), (c) \(19.1 \mathrm{~g} / \mathrm{cm}^{3}\), (d) \(2.39 \mathrm{~g} / \mathrm{cm}^{3}\), (e) \(5.72 \mathrm{~g} / \mathrm{cm}^{3}\).

Equation Transcription:

Å

Å

Å

Å

Text Transcription:

Rb^+ (1.66{AA},85.47 g/mol)

I^-(2.06{AA},126.90 g/mol)

g/cm^3

Sc^3+(0.88{AA},45.0 g/mol)

F^-(1.19{AA},19.0 g/mol)

ScF_3

5.99 g/cm^3

1.44x10^24 g/mol

19.1 g/cm^3

2.39 g/cm^3

5.72 g/cm^3