Question

A particular graduated cylinder contains 24.0 mL Br2(liquid). The density of bromine at 25 degrees C is 3.12g/cm^3. Note that in nature, elemental bromine exists in diatomic form(that is, as Br2)

How many representative particles(molecules of Br2) are in the cylinder?

Answer 1

`2.82x10^(23)molecules`

Step-by-step explanation:

Hello.

In this case, given the volume (1cm³=1mL) and density of the bromine we are to firstly compute the mass since it will allow us to compute the representative particles:

`\rho =(m)/(V)`

`m=\rho *V=3.12g/cm^3*24.0cm^3\\\\m=74.88gBr_2`

Next, since the mass of one mole of diatomic bromine is 159.82 g (one bromine weights 78.91), we can next compute the moles in that sample:

`n=74.88g*(1mol)/(159.82g) =0.469molBr_2`

Finally, via the Avogadro's number we can compute the representative particles of bromine as follows:

`particles=0.469mol*(6.022x10^(23)molecules)/(1mol)\\ \\2.82x10^(23)molecules`

Best regards.