Physical and Chemical Changes - KEY
1. Label each process as a physical or chemical change:
a. ________P__________ perfume evaporating on your skin
b. ________P__________ butter melting
c. ________C__________ wood rotting
d. ________C__________ autumn leaves changing color
e. ________P_________ a hot glass cracking when placed in cold water
f. ________P__________ melting copper metal
g. ________C__________ burning sugar
h. ________P__________ mixing sugar in water
j. _________C_________ digesting food
2. Which of the following would NOT be a physical change?
a. freezing water to make ice cubes
b. melting gold to make jewelry
c. burning gasoline in a lawnmower
d. boiling water for soup
e. tearing a piece of aluminum foil
3. Which of the following is NOT a physical change?
a. grating cheese
b. melting cheese
c. fermenting of cheese
d. mixing two cheeses in a bowl
4. Which are physical and which are chemical changes?
a. _P_________________ boil
b. _C_________________ burn (combustion)
c. _P_________________ condense
d. _C_________________ corrode
e. _P_________________ crumple
f. _C_________________ ferment
g. _P_________________ melt
h. _C_________________ rust
i. _P_________________ crush
j. _P_________________ freeze
k. _C_________________ oxidize
l. _C_________________ tarnish
m. _P_________________ sublimation
n. _P_________________ grind
o. _C_________________ rot
p. _P_________________ vaporize
q. _C_________________ photosynthesis
r. _P_________________ sublimation
5. If a certain mixture is homogeneous, you would properly conclude that the physical properties
and the composition:
a. are different from one part of the sample to another
b. vary smoothly from top to bottom of the sample
c. are the same in every small volume element from the sample
d. none of these
6. Label each process as a physical or chemical change:
a. _P_________________ Moth balls gradually vaporize in a closet
b. _C_________________ hydrofluoric acid attacks glass (used to etch glassware)
c. _C_________________ A chef making a sauce with brandy is able to burn off the
alcohol from the brandy, leaving just the brandy flavoring
d. _P_________________ Chlorine gas liquefies at -35 °C under normal pressure
e. _C_________________ hydrogen burns in chlorine gas
7. Label each process as a physical or chemical change:
a. _P_________________ fogging a mirror with your breath
b. _P_________________ breaking a bone
c. _C_________________ mending a broken bone
d. _C_________________ burning paper
e. _P_________________ slicing potatoes for fries
f. _P_________________ mixing sugar with coffee
g. _C_________________ frying chicken
h. _C_________________ a nail rusting
i. _P_________________ paper ripping
j. _C_________________ wood burning
k. _P_________________ mixing water and food coloring
l. _C_________________ food molding (rotting)
m. _P_________________ writing on paper
n. _P or C_________________ dyeing fabric
8. Calcium, an element, is a dull, gray solid that melts at 839oC. When it is placed in water,
bubbles form, as the solid calcium slowly disappears in the water. When the water is evaporated,
a white powder remains, but elemental calcium is not recovered. Which are the physical
properties of calcium? Which is a chemical property?
Chemical – highlighted in blue
Physical – highlight in red
9. A beaker of an unknown clear and colorless liquid has a volume of 100.0mL and a mass of
78.9g Initially, its temperature is 25oC. When heated, it boils at 78.5oC. If ignited, it burns
completely with a blue flame, leaving no residue behind. Which of these pieces of information
will be helpful in identifying the liquid?
Chemical – highlighted in blue
Physical – highlight in red
10. In lab, you are handed a metallic object and charged with determining its identity. What
types of things can you do to figure out what the object is made from?
Answers vary
11. A pure substance is a green solid. When heated, it gives off a colorless gas and leaves a
brown, shiny solid that melts at 1083oC. The shiny solid cannot be decomposed to simpler
substances, but the gas can. List all the properties given and tell whether they are chemical or
physical.
Chemical – highlighted in blue
Physical – highlight in red
12. A pure substance is a greenish-yellow, pungent gas that condenses to a liquid at -35oC. It
undergoes a chemical reaction with a given substance to form a white solid that melts at 801oC
and a brown, corrosive liquid with a density of 3.12 g/mL. The white solid can be decomposed to
simple substances, but the gas and the liquid cannot. List all of the properties given and tell
whether they are physical or chemical.