Question

. If a substance changes form one phase to another, is it still the same substance?

Answer 1

Answer:

Yes

Explanation:

A phase change does not change the chemical make-up of a substance.  Phase changes are typically temperature dependent, and change only the movement and physical arrangement of the atoms and molecules in the substance.  Water, for example, is composed of two hydrogen atoms attached to an oxygen atom by covalent bonds.  That stays the same whether the water is solid (ice), liquid (water), or gas (steam).  The chemical structure of water does not change as it goes through the different faces.  It's still water.  What does change is the speed at which the molecules move and how far apart they are as a result.  Water vapor consists of molecules moving quickly and at random.  As temperature drops, water molecules slow down.  Since water is slightly polar, hydrogen bonds form between the molecules bringing them closer together.