Density Question???

Question

A pycnometer weights 20.455g empty and 31.486 when filled with water. (d = 1g/cm3). Pieces of an alloy are put into the empty pycnometer. The mass of the alloy and pycnometer is 28.695g. Water is added to the alloy to exactly fill the pycnometer. The mass of the pycnometer, water, and alloly is 38.689g. What is the density of the alloy?

Any suggestions on how to start this, or guidance would be wonderful!

Answer 1

what is the volume of the container @ 1g/cc for water:

31.486 g - 20.455 = 11.031 cc volume

how much water could still fit in when the metal was there too:

38.689 - 28.695 = 9.994 grams of water = 9.994 cc of water

what is the volume of metal:

11.031 - 9.994 = 1.037 cc of metal

what is thw mass of metal:

28.695 - 20.455 = 8.240 grams of metal

what is the density of metal:

8.240g / 1.037 cc = 7.946 g /cc

that's your answer

Answer 2

First off, we find out that the volume of your pycnometer is 31.486 - 20.455 = 11.031 cm^3.

When the alloy is added, we find out that only 38.689 - 28.695 = 9.994 cm^3 of water was added.

Thus 11.031-9.994 = 1.037cm^3 is how much space the alloy occupies.

The alloy weighs 28.695 - 20.455 = 8.24 grams.

density is weight/volume so density of alloy is 8.24/1.037 = 7.946 g/cm^3