When finding the density of a liquid, why must you first find the mass of a graduated cylinder alone?

1 Answer
Nov 1, 2016

Answer:

Let's start with #"density"#. How do we define it?

Explanation:

#"Density, "rho# #=# #"Mass"/"Volume"#.

Now clearly, when we make such a measurement, it is useful to measure a large mass, and a large volume simultaneously to make the measurement. So take a #100*mL# graduated flask, measure the tare, i.e. the empty mass #(i)#, and then fill it to volume, and then take the mass #(ii)# when full.

#(ii)-(i)# is the mass of the liquid, and thus, #rho=underbrace((ii)-(i))_"mass of liquid"/underbrace(100*mL)_"volume of liquid"# with units of #g*mL#, or equivalently #g*cm^-3#. Is this what you want?