1-7 Physical and Chemical Changes

Question 1

Physical Change

Answer 1

A change that does not entail any
change in chemical composition
ex:
Solid iron (Fe) melting in a blast furnace Fe(s) → Fe(l)
 Ice cube melting
H2O(s) → H2O(l)
 dissolving a solid in a liquid to give a
homogeneous mixture — a SOLUTION.

Question 2

Chemical Change

Answer 2

-Involves a change in chemical composition
-Results in a change in composition or structure
ex: Magnesium metal burns in air
with a bright white flame to form
a white solid, magnesium oxide
2Mg + O2  2MgO

Question 3

Chromatography

Answer 3

-separated components of mixture
-didn’t change the components

Question 4

Electrolysis

Answer 4

water was changed to hydrogen and
oxygen

Question 5

Which of the following is NOT a physical change?
a. the freezing of a liquid to form a solid
b. dissolving a solid in water to form a
solution
c. burning a piece of paper
d. evaporating water to steam
e. sublimation of ice to water vapor

Answer 5

c

Question 6

Which one of the following is a chemical change?
a. The metallic layer in some mirrored
sunglasses reflects sunlight.
b. The color of the dye in a red shirt left in the
sun fades over time.
c. A crystal of table salt (NaCl) shatters when
struck with a hammer.
d. Water boils at 70 °C on top of Chomolungma
(Mt. Everest).

Answer 6

b