Answer to Question #302940 in General Chemistry for Anson

Question

A pycnometer, nominally 10 ml, was found to have a volume of 9.9872 ml, when filled

exactly to the top of the capillary in the stopper. The pycnometer was filled with benzene

(an organic liquid), and weighed. The mass of the filled pycnometer was found to be

21.8743 g. The pycnometer empty was weighed, and found to have a mass of 13.1455 g.

Calculate the density of the benzene. Compare this to the density of benzene at 25.0 0C

that you find in the literature

Answer 1

AConsidering the definition of density and after a short literature search, the density of water is 1.0044 g/mL and the experiment was performed at 4 °C.

First off, keep in mind that density can be defined as the mass of a substance per unit volume, and may be expressed in g/mL.

Now we calculate the mass of the water, using the given masses of the empty and filled pycnometer:

• mass of water = 23.1455 g - 13.1148 g = 10.0307 g

As the pycnometer volume is 9.9872 mL, we can calculate the density of water:

• density = mass / volume = 10.0307 g / 9.9872 mL = 1.0044 g/mL

The density of water varies by temperature, with it being at its highest at 4 °C, with a reported value of 1.00 g/mL. Given that the value obtained in the experiment is above 1 g/mL, it is safe to assume that the experiment was performed at 4 °C.