Questions: Grams, Moles, Atoms, Molecules Show calculation setups, including units, and enter answers with correct significant figures and units on the line(s) provided. 1. Find the molar mass to 3 decimal places of (a) magnesium sulfate, (b) diphosphorus heptaoxide, and (c) iron(III) hydroxide. Use these values as needed in problems 2-4. (a) (b) (c)

Solution Steps

To find the molar mass of magnesium sulfate, sum the atomic masses of all atoms in the formula:

• Magnesium (Mg): 24.305 g/mol
• Sulfur (S): 32.065 g/mol
• Oxygen (O): 16.00 g/mol (4 atoms)

\[ \text{Molar mass of MgSO}_4 = 24.305 + 32.065 + (4 \times 16.00) = 24.305 + 32.065 + 64.00 = 120.370 \text{ g/mol} \]

To find the molar mass of diphosphorus heptaoxide, sum the atomic masses of all atoms in the formula:

• Phosphorus (P): 30.974 g/mol (2 atoms)
• Oxygen (O): 16.00 g/mol (7 atoms)

\[ \text{Molar mass of P}_2\text{O}_7 = (2 \times 30.974) + (7 \times 16.00) = 61.948 + 112.00 = 173.948 \text{ g/mol} \]

To find the molar mass of iron(III) hydroxide, sum the atomic masses of all atoms in the formula:

• Iron (Fe): 55.845 g/mol
• Oxygen (O): 16.00 g/mol (3 atoms)
• Hydrogen (H): 1.008 g/mol (3 atoms)

\[ \text{Molar mass of Fe(OH)}_3 = 55.845 + (3 \times 16.00) + (3 \times 1.008) = 55.845 + 48.00 + 3.024 = 106.869 \text{ g/mol} \]

Final Answer