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Example 3.7: Deriving Grams from Moles for a Compound

Vitamin C is a covalent compound with the molecular formula \(\ce{C6H8O6}\). The recommended daily dietary allowance of vitamin C for children aged 4–8 years is \(1.42\times 10^{-4 }\)mol. What is the mass of this allowance in grams?

Solution

\(n_{\mathrm{VitC}}\) \(= 1.42\times 10^{-4}\ \mathrm{mol}\)


\(m_{\mathrm{VitC}}\) = ?


As for elements, the mass of a compound can be derived from its chemical amount as shown:

The molar mass for this compound is computed to be 176.124 g/mol. The given amount is a very small fraction of a mole (~10^-4 or one-ten thousandth); therefore, we would expect the corresponding mass to be about one-ten thousandth of the molar mass (~0.02 g). Performing the calculation, we get:

\(m_{\mathrm{VitC}}\) \(= n_{\mathrm{VitC}} \cdot M_{\mathrm{\ce{C6H8O6}}}\)

\(\ \ \ =1.42\times 10^{-4}\ \mathrm{mol} \cdot 176.12\ \frac{\mathrm{g}}{\mathrm{mol}}\)

\(\ \ \ =0.0250\ \mathrm{g}\)


This is consistent with the anticipated result.