posted by anonymous .
i neeed help determining whether the following changes are chemical or physical and why. i have some guesses but i wanted to have them verified. thanks. =)
1) mixing chalk and vinegar: chem. b/c it bubbles
2) mixing starch and iodine: physical b/c the iodine dissoles and the satrch falls to the bottom of the beaker, (but the mixture turns purple)
3) ammonia abd iron (III) chloride: physical b/c the mixture eventually settles out,(but there is a color change.)
please help me to verify. thanks