A sample contains magnesium hydroxide. What is the molar mass of Mg(OH)_2?

• A. 34.08 g/mol
• B. 58.32 g/mol
• C. 40.30 g/mol
• D. 74.09 g/mol

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the compound, which is Mg(OH)\_2, meaning it contains 1 magnesium (Mg) atom, 2 oxygen (O) atoms, and 2 hydrogen (H) atoms.
2. Find the atomic masses of each element from the periodic table: magnesium (Mg) ≈ 24.31 g/mol, oxygen (O) ≈ 16.00 g/mol, and hydrogen (H) ≈ 1.01 g/mol.
3. Calculate the total mass contributed by each element by multiplying the atomic mass by the number of atoms in the formula: for Mg, multiply by 1; for O, multiply by 2; for H, multiply by 2.
4. Add the masses of all elements together to get the molar mass of Mg(OH)\_2 using the formula: \(\text{Molar mass} = (1 \times M_{Mg}) + (2 \times M_{O}) + (2 \times M_{H})\).
5. Sum these values to find the total molar mass of magnesium hydroxide, which will help you identify the correct answer from the given options.