Question

Liquid Bromine, Br2, has a density of 3.53g/mL. How many bromine molecules are in 15.0 mL of bromine?

Answer 1

To calculate the number of bromine molecules in 15.0 mL of liquid bromine, multiply the volume by the density to find the mass, convert the mass to moles using the molar mass of bromine, and then use Avogadro's number to find the number of molecules.

Step-by-step explanation:

The question asks about the number of bromine molecules present in 15.0 mL of liquid bromine with a density of 3.53 g/mL. To find the number of molecules, we first calculate the mass of bromine in 15.0 mL using the formula mass = density × volume.

After finding the mass, we convert that mass to moles using the molar mass of bromine, which is approximately 159.808 g/mol for Br2 (the molecular form of bromine). Finally, to find the number of molecules, we use Avogadro's number (6.022 × 1023 molecules/mol).

Here are the step-by-step calculations:

1. Calculate the mass of 15.0 mL of bromine: mass = 3.53 g/mL × 15.0 mL = 52.95 g.
   
2. Calculate the number of moles of bromine: moles = 52.95 g × (1 mol/159.808 g) ≈ 0.331 mol.
   
3. Calculate the number of molecules of bromine: 0.331 mol × (6.022 × 1023 molecules/mol) ≈ 1.99 × 1023 molecules.