Question

A pycnometer weighs 25.60 g empty and 35.55 g when filled with water at 20°C. The density of water at 20°C is 0.9982 g/ml. When 10.20 g lead is placed in the pycnometer and the pycnometer is again filled with water at 20°C, the total mass is 44.83 g. What is the density of the lead in grams per cubic centimetre?

Answer 1

Answer:

11.07 g/cm³

Explanation:

• Using the first difference in mass we can calculate the volume it takes to fill up the pycnometer:

35.55 - 25.60 = 9.95 g of water

9.95 g / 0.9982g/mL = 9.9679 mL

• In order to calculate the volume occupied by lead, we calculate the volume of water, using again the difference in mass:

44.83 - 10.20 - 25.60 = 9.03 g water

9.03 g / 0.9982g/mL = 9.0463 mL water

The volume that is not occupied by water, is occupied by lead:

9.9679 - 9.0463 = 0.9216 mL

With the volume occupied by lead, and the mass, we can calculate the density of lead, keeping in mind that 1 mL = 1 cm³:

10.20 g / 0.9216 cm³ = 11.07 g/cm³.