A 38.0-g sample of the chlorofluorocarbon CF2Cl2 is analyzed. How many grams of chlorine (Cl) are present in the sample? (Atomic masses: C = 12.0 g/mol, F = 19.0 g/mol, Cl = 35.5 g/mol)

• A. 38.0 g
• B. 7.1 g
• C. 10.7 g
• D. 21.3 g

Answer: (D)

Verified step by step guidance

1. Determine the molar mass of CF2Cl2 by summing the atomic masses of all atoms in the molecule: \(M = (1 \times 12.0) + (2 \times 19.0) + (2 \times 35.5)\) g/mol.
2. Calculate the mass fraction of chlorine in CF2Cl2 by dividing the total mass of chlorine atoms by the molar mass of CF2Cl2: \(\text{mass fraction of Cl} = \frac{2 \times 35.5}{M}\).
3. Multiply the mass fraction of chlorine by the total sample mass to find the mass of chlorine in the 38.0-g sample: \(\text{mass of Cl} = \text{mass fraction of Cl} \times 38.0\) g.
4. Set up the calculation clearly to ensure units are consistent and the arithmetic follows the formula correctly.
5. Interpret the result as the grams of chlorine present in the sample without rounding prematurely.