Final answer:
The percentage composition of CF4 is 13.6% carbon and 86.4% fluorine. The percentages are calculated based on the molar masses of carbon and fluorine and the molecular formula of CF4.
Step-by-step explanation:
The question asks us to calculate the percentage composition of CF4 (carbon tetrafluoride). To find this, we need the molar masses of carbon (C) and fluorine (F) from the periodic table. Carbon has a molar mass of approximately 12.01 g/mol and fluorine has a molar mass of approximately 19.00 g/mol. Since CF4 has one carbon atom and four fluorine atoms, its molar mass is 12.01 g/mol (for carbon) + 4 × 19.00 g/mol (for fluorine), which equals to 88.01 g/mol for the entire molecule.
To calculate the percentage by mass of carbon in CF4, we take the molar mass of carbon (12.01 g/mol) and divide it by the molar mass of the entire compound (88.01 g/mol), and then multiply by 100 to get a percentage:
(12.01 g/mol / 88.01 g/mol) × 100 = 13.65%, approximately 13.6%
Similarly, to calculate the percentage by mass of fluorine, we take the molar mass of fluorine in the compound (4 × 19.00 g/mol = 76.00 g/mol) and divide by the molar mass of the compound, and multiply by 100:
(76.00 g/mol / 88.01 g/mol) × 100 = 86.35%, approximately 86.4%
Thus, the percentage composition of CF4 is 13.6% C and 86.4% F, which corresponds to answer choice A).