Question

How many liters of `Br_2` are in a container at STP that contains 2.25 moles of `Br_2`?

Answer 1

Approx. `100` `mL` . Why?

Explanation:

We need to know the density of elemental bromine. `rho` `=` `3.11` `g*mL^-1` at STP.

Now there are `2.25` `mol` of stuff; i.e. there are `2.25` `cancel(mol)` `xx` `2xx79.90` `g*cancel(mol^-1)` `=` `359.55` `g`. (Note that I mulitplied by 2 in order to account for the molecularity of elemental bromine; it is `79.9` `g*mol^-1` for the bromine ATOM!)

Using the density, `rho`, this is `(359.55*cancelg)/(3.11*cancelg*mL^-1)` `~=` `100` `mL` `=` `??L`

There are few things in the laboratory that are as corrosive as bromine; it can cause horrendous burns, and this quantity would be treated with respect.