Experiment #1: Physical and Chemical Changes
Precautions: Safety glasses, safety aprons,   DO NOT look directly at the burning magnesium.
 
Objective: To study the difference between a physical and a chemical change.
 
Apparatus: Bunsen burner, crucible tongs, medium test tubes, ceramic tile, mortar and pestle
 
Materials: Wood splints, copper strip, magnesium ribbon, sandpaper, sugar, glass rod, table salt
 
Procedures:
1.    . Examine a wood splint and note its physical properties in the table below. Heat the splint until it takes fire and allow it to burn itself out on the ceramic tile. Record your observations in the table below.
2. Using a test tube holder, heat 1/6 of a test tube of water in a test tube until it boils. Hold a dry test tube in the escaping steam for a minute or two. What is the product that condenses on the tube? ________________ Record your observations in the table below.
 
3. Scour a piece of copper with sandpaper until it is perfectly clean. Examine it and note its properties. Hold the copper strip with the tongs and heat it in the Bunsen burner for several minutes. Examine and note its properties after heating. Record your observations in the table below.
 
4. Put a pinch of sugar in a dry test tube. Heat the test tube for several minutes. Note the properties of the sugar before and after heating. Record your observations in the table below.
 
5. Heat the end of a glass rod until it becomes soft and bends. When cool, examine and compare the heated with the unheated end of the rod. Record your observations in the table below.
 
6. Clean the magnesium ribbon with sandpaper. examine the magnesium and note its properties. Hold the magnesium strip with the tongs and ignite it in the Bunsen burner.
 
7.  Taste some salt. Place 1/2 cm3 of salt in a clean mortar and pestle and grind it to a powder. Taste the ground salt. Dissolve some of the salt in « test tube of water. Taste the solution. Record your observations in the table.
 
 

Observations:   Table of Observations
 Materials   Properties Before Heating   Properties After Heating   Chemical or Physical Change? 
Wood            
Water            
Copper            
Sugar            
Glass            
Magnesium            
    Salt            Taste of 
       Crystals 
     Taste when 
       Ground 
   Taste when 
    Dissolved





 
Summary Questions:
1. Different kinds of matter are recognized by observing their _________________________.
 
2. Five characteristics or properties used to identify substances are ______________________

______________________________________________________________________________.
 

3. Two kinds of changes that matter may undergo are _______________________ and 

______________________.
 

4. A change in which a substance loses the properties by which we identify it is called a

_____________________ change.
 

5. A change in which an element or compounds may change some of its physical properties but not

its chemical properties is called a _____________________ change.
 

Conclusions:
1. A chemical change is one in which ___________________________________________

_______________________________________________________________________.
 

2. Compounds are formed as the result of __________________________ changes.
 
3. A physical change is one in which _______________________________________________

___________________________________________________________________________
 

4. The formation of mixtures is a ______________________ change.
 
Related Questions:
1. Matter is defined as ________________________________________________________.
 
2. The three states or forms of matter are _________________________________________.
 
3. Mixing iron fillings and sulphur is a ____________________ change because _________

__________________________________________________________________________
 

4. Heating a mixture of iron filings and sulphur produces a _______________ change because

__________________________________________________________________________
 

5. State whether the following are Physical (P) or chemical (C) changes:

a) Souring of milk _______                           g) Burning of coal _______

b) Rusting of iron _______                            h) Pulverizing sugar _______

c) Breaking glass _______                            i) Boiling water ________

d) Tarnishing of silver _______                     j) Melting ice ________

e) Dissolving salt in water ______                k) Melting paraffin _______

f) Magnetizing iron _______                         l) Decaying of food _______
 

6. Does the application of heat to a substance always produce a chemical change? _______ Give

examples to support your answer _________________________________________
 

7. Give an example of a chemical change produced by:

a) Light ________________________________________________

b) Electricity ___________________________________________

c) Heat ________________________________________________
 

8. Give an example of a chemical change which produces:

a) Light and Heat ________________________________________

b) Electricity ___________________________________________

c) Mechanical energy ____________________________________
 

9. How would you show that:

a) dissolving sugar in water is a physical change.

b) heating a platinum wire in air is a physical change.