A special flask used in the determination of densities, called a pycnometer, has a mass of 16.3179 g when empty, and it has a mass of 48.0250 g when filled with water at 20.0°C.When this same pycnometer is filled with ethyl alcohol at 20.0°C, it is found to have a mass of 41.3934 g.Find the density of ethyl alcohol at 20.0°C. (Given: at 20.0°C, the density of water is 0.9982 g/mL)
A)0.7894 g/mL
B)0.7923 g/mL
C)0.7908 g/mL
D)1.303 g/mL
E)0.7674 g/mL

Question

Quizplus · Accepted Answer

The mass of the water is 48.0250 g - 16.3179 g = 31.7071 g. Using the density of water (0.9982 g/mL), the volume of the pycnometer is 31.7071 g / 0.9982 g/mL = 31.764 mL. The mass of ethyl alcohol is 41.3934 g - 16.3179 g = 25.0755 g. The density of ethyl alcohol is 25.0755 g / 31.764 mL = 0.7894 g/mL.

A Special Flask Used in the Determination of Densities, Called