Question

How is density used in chemistry?

Answer 1

For a practising chemist (i.e. one on the bench), density is used to approximate mass, i.e. amount of substance, by measuring volume.

Explanation:

`"Density "rho` `=` `"Mass"/"Volume"`

Thus `"Mass"` `=` `"density "xx" volume"`.

And thus a stoichiometric mass of chemical can be introduced by delivery of a known volume of reagent. The reagent necessarily must be a fluid, i.e. a gas, or more generally, a liquid. `5-10*mL` syringes (and smaller and larger volumes) are routinely used by by synthetic chemists to withdraw given volumes of air-sensitive reagent. The syringes are typically purged first a couple of times with inert gas, so that the atmosphere does not react with the reagent during transfer.