IPC- physics and chemistry?

Question

can anyone help me w/ this

would a cube of solid silver sink or float in liquid silver? how ?
&
at 20* oC, the density of copper is 8.9 g/cm cubed. the denstiy of platinum is 21.4g/cm cubed. what does this tell you about how the atoms are "packed in each material?

thank you

Answer 1

1.) would a cube of solid silver sink or float in liquid silver? how ?

For almost all compounds except water, the solid is denser than the liquid and will sink. Water is an exception because ice forms a crystelline matrix - silver does not. Thus, solid silver will sink in liquid silver.

2.) at 20* oC, the density of copper is 8.9 g/cm cubed. the denstiy of platinum is 21.4g/cm cubed. what does this tell you about how the atoms are "packed in each material?

density of copper is 8.9 g/cm^3, but the atomic weight is 29.
density of platinum is 21.4 g/cm^3 but the atomic weight is 78

Density is a function of both the atomic weight and how well the atoms are packed - if the ratio of the atomic weights is the same as the ratio of densities, then the packing of atoms has no effect.

Platinum is 2.404 times as dense, and 2.69 times the atomic weight, thus, the atoms are slightly more densely packed for platinum than copper.