What is the percent by mass of chlorine in FeCl_3?

• A. 35.0%
• B. 25.0%
• C. 65.0%
• D. 45.0%

Answer: (C)

Verified step by step guidance

1. Identify the chemical formula of the compound, which is FeCl_3, meaning it contains 1 atom of iron (Fe) and 3 atoms of chlorine (Cl).
2. Find the atomic masses of each element from the periodic table: iron (Fe) has an atomic mass of approximately 55.85 g/mol, and chlorine (Cl) has an atomic mass of approximately 35.45 g/mol.
3. Calculate the total molar mass of FeCl_3 by adding the atomic mass of iron and three times the atomic mass of chlorine: \(M_{FeCl_3} = M_{Fe} + 3 \times M_{Cl}\).
4. Calculate the total mass of chlorine in one mole of FeCl_3 by multiplying the atomic mass of chlorine by 3: \(Mass_{Cl} = 3 \times M_{Cl}\).
5. Calculate the percent by mass of chlorine in FeCl_3 using the formula: \(\% \text{Cl} = \left( \frac{Mass_{Cl}}{M_{FeCl_3}} \right) \times 100\%\).