Physical and Chemical Properties Lab

INTRODUCTION:

Matter has characteristics, called properties, which help us identify and describe it. Properties can be considered either physical properties or chemical properties. Physical properties are things like: color, odor, density, hardness, structure, solubility, melting point and boiling point temperatures. These are considered physical because they can be detected without changing the nature of the material. Chemical properties are determined by a reaction of a substance with another substance. A new substance with new properties is formed during the chemical reaction. Examples are things like: combination with acid or base, burning (also called combustion), oxidation (like corrosion or rusting) or changing it into another compound.

A few changes are difficult to know at first if they are chemical or physical changes. The basic test is that if the shape, size or physical state is altered, but the chemical composition remains the same, then it is a physical change. If a new substance with a new chemical make up is formed, then a chemical change or chemical reaction has occurred. In a chemical reaction the atoms of the substance have been rearranged.

PURPOSE:

Students will carry out several procedures, collecting both qualitative and quantitative data, and determine in each case whether a physical or chemical change has taken place.

MATERIALS:cobalt chloride hydrate (CoCl2·6H2O)

evaporating dishsodium chloride (NaCl)one small test tube

watch glass6M ammonia (NH3)two medium test tubes

ring stand0.1M silver nitrate (AgNO3)solid rubber stopper #1

Bunsen burnercopper wire (Cu)wire gauze

iron ringdistilled waterscoopula

Before Beginning: Set up a data table to record all observations for each part of the lab. Put on goggles, apron and shoes. Tie long hair back away from face.

Procedure A:

  1. Add a scoop of sodium chloride to a medium test tube. Fill the tube about half way with distilled water. Put a solid rubber stopper to fit and shake. Record your observations.

Procedure B:

  1. Pour half of your sodium chloride solution into an evaporating dish and leave half in the test tube. Use the evaporating dish in part D.
  2. Add several drops of silver nitrate solution (0.1M AgNO3) to the test tube. Mix by swirling the tube using the Cornell method. Record your observations.

Procedure C:

  1. Add several drops of ammonia(6M NH3) to the tube from part B. Quickly put the cap back on the ammonia as well as the solid stopper on the tube. Gently swirl the tube to mix the solutions. Record your observations.
  2. Rinse the contents of the tube down the drain with plenty of water.

Procedure D:

  1. Place the evaporating dish with the sodium chloride solution from part B, onto a wire-gauze placed upon an iron ring. Be sure the iron ring is first secured to the ring stand a few centimeters above the top of a laboratory burner. Place a watch glass over the evaporating dish (use the watch glass like a bowl, not like a dome).
  2. Heat the solution until boiling and then turn down the heat and simmer until all the moisture is gone.
  3. Turn off the burner and LET THE APPARATUS COOL FOR AT LEAST 10 MINUTES. You may go on to another part of the lab and come back to finish after it has cooled.
  1. After it is only slightly warm when you place the back of your hand close to the dish, examine the material inside the evaporating dish. Record all observations.
  2. Clean the dish and watch glass in the sink.

Procedure E:

  1. Fold up a copper wire and place it inside a small test tube. Cover the wire with silver nitrate solution. Set the tube aside for 10 minutes. Return later and record all observations.
  2. Carefully, dump the solid contents of the tube into the trash, rinsing the test tube with a water bottle.

Procedure F:

  1. Place a small scoop of cobalt chloride hydrate into an evaporating dish. Heat it slowly until it dries. Record your observations.
  2. Turn off the burner and LET THE DISH COOL FOR AT LEAST 10 MINUTES. After it has cooled add some water to the dried solid. Record your observations.

Data Table:

Part: / Observations
A
B
C
D
E
F

Analysis:

Analyze each change in parts A-F. Determine if it was a physical or chemical change, citing evidence from your observations to help explain why it was that particular type. (No evidence, no credit!!)

Conclusion:

Using the specific examples you saw in this activity, summarize a general method of determining if a change is physical or chemical.

The lab report must be written up and include a title, purpose, data table, analysis and conclusion. (see rubric on page 14 in your packet)