Name_______________________________________
Identification of Physical and Chemical Changes
Principles and Procedures: While a physical property can be observed without altering the identity of a material,
a chemical property cannot. Chemical properties are observed when substances are converted to different
substances with different properties. Flammability, for example is a chemical property that can only be observed
when a substance reacts with oxygen. If a chemical change has occurred, the products differ from the reactants.
Certain easily observed changes that generally indicate a chemical reaction has occurred: (a) the simultaneous
production of light and heat; (b) the production of a gas when two or more substances are mixed; (c) the
formation of a precipitate when two or more solutes are dissolved in a solution; (d) a color change occurs; or (e)
an odor is produced.
Make careful observations of the following actions. On the basis of your observations, indicate whether a
physical or chemical change has occurred. Also indicate the evidence for your answer. Your evidence needs to be
detailed or you will lose points.
Activity
1. Adding vinegar to
baking soda
2. Melting an ice cube
3. Dissolving sugar in
water
4. Adding vinegar to milk
(let it sit 3-4 minutes)
5. Crushing rock salt in a
mortar and pestle
6. Bromthymol blue and
vinegar
7. Magnesium nitrate
and sodium hydroxide
8. Burning magnesium
Chemical or
Physical Change
Evidence
Questions:
1. Identify the following as chemical (C)or physical (P) changes.
a. Melting ice____ b. burning paper_____ c. digesting food _______
d. cutting paper ______
2. What is the purpose in observing a reaction immediately and then again after 5 minutes?
3. List 4 things that indicate a chemical change has taken place.
4. A change in energy is often indicated by a change in temperature. Why should you feel the outside of the
test tube after each chemical is added?
5. Identify each of the following as an element, compound, or mixture.
a.
b.
c.
d.
Hydrogen gas (H2)________________________ e. koolaid___________________________
Sodium chloride (NaCl)____________________ f. pond water________________________
Alcohol and water________________________ g. sulfur (S) _________________________
Pepsi (pop) _____________________________ h. silver (Ag)_________________________
6. Sodium chloride (salt) dissolves in water forming a clear solution with no physical evidence of the crystals
you started with. What could you do to separate the salt from the water?
7. Determine how many different elements are in each compound below.
a. Carbon dioxide CO2
________
c. Sodium bicarbonate (baking soda) NaHCO3 ______
b. Sucrose (sugar) C12H22O11
________
d. Calcium bromide CaBr2
______
8. Ethyl alcohol (C2H5OH), Sucrose (C12H22O11), and Vinegar (HC2H3O2) and all made up of just Carbon,
Hydrogen, and Oxygen. What does this tell you about the make up of a compound?
9. Matching:
_____ salt water
_____oil and water
_____pepperoni pizz
_____steel
a. homogeneous
b. heterogeneous
10. Classify the following properties as physical (P) or chemical (C).
a. Color
_____
d. burns easily _____
O
b. Melts at 68
_____
e. reacts with oxygen _____
c. Not affected by acids _____
f. malleable ______
g. density _____
h. conducts electricity _____
i. dissolves in water ______