# Determine the density of a unknown liquid by Pycnometer method? Volume of Pycnometer?

a STUDENt collected the following date to determine the density of an unknown liquid by the pycnometer method:

Mass of dry pycnometer and stopper: 32.4345g

Mass of pycnometer + stopper +water: 58.0558g

Mass of pycnometer + stopper + unknown liquid: 52.8734g

Temperature of the water: 23.0 deg C

the temp is used to find the density of the water at that temp which i have found to be: 0.997538

1) Calculate the volume of the Pycnometer

2)Determine the density of your unknown liquid

I honestly have no idea how to answer these 2 questions. Can someone please explain? Thank You

• take the mass of the pycnomete + stopper + unknown liquid and subtract the mass of the pycnometer + stopper

52.8734g – 32.4345g = [mass of unknown liquid]

Then find the volume of the unknown liquid, which is the same as the volume of the pycnometer, which is the same as the volume of water inside the pycnometer.

the volume of water is the mass of water: mass of stopper+pycnometer+water – mass of pycnometer+stopper

58.0555g – 32.4345g = [mass of water]

Then use the density of water to determine the volume of water:

d= m/v == v=m/d

v = [mass of water] 0.997535g/cm^3

now you have the volume of the pycnometer and the mass of your unknown liquid.

to find the density of that liquid just divide the liquid’s mass by the volume of the pycnometer.

• Pycnometer Method