Density Difference Between Solid and Molten Copper

What is the difference in density between solid copper and molten copper?

The density of solid copper is 8960 kg/m3, while the density of molten copper is 7900 kg/m3. How can this difference be explained?

Answer:

The difference in density between solid copper and molten copper is due to changes in the arrangement of atoms and their degree of movement. Solid copper atoms are tightly packed in a regular pattern while molten copper atoms are more freely arranged. This difference in arrangement affects the volume of the substance, leading to variations in density.

Explanation: The density difference between solid and molten copper can be explained using the particle model. In solid copper, the atoms are tightly packed together in a regular pattern, resulting in a higher density of 8960 kg/m3. When copper transitions to a molten state, the atoms gain greater kinetic energy and move more freely, causing a slightly expanded and less regular arrangement. This leads to the lower density of molten copper, which is 7900 kg/m3.

With reference to the arrangement of atoms, the solid state of copper exhibits a close-packed atomic arrangement due to the strong forces of attraction between atoms. However, in its molten state, the thermal energy overcomes these forces and atoms move apart, resulting in a less dense and more fluid structure.

This difference in density can be calculated using the formula Density = Mass/Volume. In the case of copper, the change in arrangement of atoms between the solid and molten states results in a decrease in density when transitioning from solid to molten copper.