Label the following as chemical of physical changes.
a. Phase Changes –
b. Rusting iron –
c. Grinding quartz into sand –
d. Digesting food –

Question

Label the following as chemical of physical changes.
	      a.  Phase Changes –
	      b.  Rusting iron – 
	      c.  Grinding quartz into sand – 
	      d.  Digesting food –

jamesj · Answer

chemical OR physical changes. A chemical change occurs when two or more atoms or molecules react to form new molecules. A physical change does not change the chemical make up of the molecules involved, for example, boiling water doesn't change the H2O water molecules into anything else, it just puts them in a different state: liquid to gas. Hence the answer to part (a) is physical, because all phase changes (solid <-> liquid <-> gas) do not involve chemical reactions. Make sense?

anonymous · Answer

The rusting of iron is a CHEMICAL reaction of iron (Fe) and oxygen (O2) to form a NEW molecule (iron (iii) oxide or iron(ii) oxide or iron(ii,iii) oxide). (words of particular interest are in CAPITAL letters.)

Grinding quartz into sand is analogous to shredding cheese. If you take a block of cheese and shred it, what do you have? Cheese, right?

Digesting food is a complex chemical reaction. Let's take the metabolism of glucose as an example. Our body breaks down the C6H12O6 (with oxygen) into carbon dioxide and water.