Question

classify each change as physical or chemical

a/ sugar burns when heated in a skillet

b/ sugar dissolves in water

c/ a platinum ring becomes dull because of continued abrasion

d/ a silver surface becomes tarnished after exposure to air for a long period of time

Answer 1

a. sugar burns when heated in a skillet

C12H22O11 + 35/2O2 ----> 12CO2 + 11H2O ic a chemical change

b. sugar dissoves in waterto form sugar solution . On evapourate water sugar left. So it is physical change.

c.a platinum ring becomes dull because of continued abrasion is a physical changebecause of colour change only.

d.a silver surface becomes tarnished after exposure to air for a long period of time is a chemical change

4Ag+O2(air)--->2 Ag2O is chemical change.