Final answer:
To find the number of bromine atoms in 39.2 g of CH₂Br₂, calculate the moles of CH₂Br₂ and then multiply by Avogadro's number and by 2, yielding approximately 2.71 x 10²³ bromine atoms.
Step-by-step explanation:
To determine how many bromine atoms are present in 39.2 g of CH₂Br₂, first, calculate the molar mass of CH₂Br₂. This is achieved by adding the atomic masses of one carbon atom (12.01 g/mol), two hydrogen atoms (about 1.01 g/mol each), and two bromine atoms (about 79.9 g/mol each). Summing these up provides a molar mass of approximately 173.82 g/mol for CH₂Br₂.
Next, use the formula:
Number of moles = mass of substance (g) / molar mass (g/mol)
By substituting the given mass of the substance, 39.2 g, into the formula, you find the moles of CH₂Br₂:
39.2 g CH₂Br₂ / 173.82 g/mol = approximately 0.2255 mol CH₂Br₂
Each molecule of CH₂Br₂ contains two bromine atoms. Therefore, to find the total number of bromine atoms, multiply the moles of CH₂Br₂ by Avogadro's number (6.022 × 10²³ atoms/mol) and then by 2:
(0.2255 mol CH₂Br₂) × (6.022 × 10²³ atoms/mol) × 2 ≈ 2.71 x 10²³ bromine atoms