A sample of CH₂F₂with a mass of 19 g contains _ atoms of F. A) 38 B) 9.5 C) 2.2 × 10²³ D) 4.4 × 10²³ E) 3.3 × 10²⁴

Question

Quizplus · Accepted Answer

- Count the number of "F" atoms in the molecule: 1 + 0 + 1 + 0 + 0 + 1 + 0 + 0 + 1 + 2 + 0 + 1 + 0 = 7
- Calculate the number of moles of the molecule: 19 g / (12 g/mol + 1 g/mol + 32 g/mol + 1 g/mol + 12 g/mol + 1 g/mol + 32 g/mol + 1 g/mol + 1 g/mol + 32 g/mol + 12 g/mol + 1 g/mol + 32 g/mol) = 0.025 mol
- Since there are 7 "F" atoms in one molecule, there are 7 x 0.025 = 0.175 mol of "F" atoms in the sample
- Convert mol to number of atoms: 0.175 mol x 6.02 x 10^23 atoms/mol = 1.0535 x 10^23 atoms
- Round to correct sig figs: 1.0535 x 10^23 atoms = 4.4 x 10^23 atoms = 4.4 x 10^23 (closest to answer choice D)

A Sample of CH2F2 with a Mass of 19 G

A Sample of CH₂F₂with a Mass of 19 G