High School

A student received 65 µL of Br₂. How many mg of molecular bromine does that correspond to?

a) 130 mg
b) 65 mg
c) 32.5 mg
d) 97.5 mg

Answer :

Calculating the mass of molecular bromine given its volume requires knowing the density, which is typically 3.12 g/cm^3 for bromine. Using this density, the mass for 65 microliters of bromine is calculated to be 202.8 mg, hence none of the answer is correct.

To calculate the mass of molecular bromine (Br₂) that corresponds to a volume of 65 microliters (μL), we need to know the density of bromine. However, without being provided with the density, we cannot calculate the mass directly. Typically, the density of liquid bromine at room temperature is around 3.12 g/cm3.

If we assume this density, the calculation would be as follows:

First, convert the volume from microliters to milliliters:

  • 65 μL = 0.065 mL

Then, convert milliliters to cubic centimeters, which is a straightforward conversion since 1 mL is equivalent to 1 cm3:

  • 0.065 mL = 0.065 cm3

Next, use the density to find the mass:

  • Mass = Volume x Density
  • Mass = 0.065 cm3 x 3.12 g/cm3
  • Mass = 0.2028 g

Lastly, convert grams to milligrams:

  • 0.2028 g = 202.8 mg

Therefore, the exact answer is 202.8 mg, which means none of the provided options (a, b, c, d) are correct.