What is the mass percent of Mg in the compound Mg_3(PO_4)_2?

• A. 35.0%
• B. 23.0%
• C. 28.1%
• D. 18.2%

Answer: (C)

Verified step by step guidance

1. Identify the chemical formula of the compound: \(\mathrm{Mg_3(PO_4)_2}\), which contains 3 magnesium (Mg) atoms, 2 phosphate (PO\(_4\)) groups.
2. Calculate the molar mass of each element: Mg has an atomic mass of approximately 24.31 g/mol, P is about 30.97 g/mol, and O is about 16.00 g/mol.
3. Calculate the molar mass of the entire compound by summing the masses of all atoms: multiply the number of atoms by their atomic masses and add them together. For example, total Mg mass = \$3 \times 24.31\( g/mol, total P mass = \)2 \times 30.97\( g/mol, total O mass = \)8 \times 16.00$ g/mol (since there are 2 phosphate groups, each with 4 oxygens).
4. Sum all these contributions to find the molar mass of \(\mathrm{Mg_3(PO_4)_2}\): \(M_{\mathrm{compound}} = M_{\mathrm{Mg}} + M_{\mathrm{P}} + M_{\mathrm{O}}\).
5. Calculate the mass percent of Mg by dividing the total mass of Mg by the molar mass of the compound and multiplying by 100%: \(\%\mathrm{Mg} = \left( \frac{3 \times 24.31}{M_{\mathrm{compound}}} \right) \times 100\%\).