Evidence of Chemical Change Lab Background
Before completing this lab, you should have a clear understanding of:
What the difference is between a physical change and a chemical change.
The five (5) observations indicate a chemical change has occurred. Problem:
What observable changes happen when a chemical change occurs as opposed to a physical change?
Experiment Materials:
• dilute hydrochloric acid • 1 piece of zinc metal
• phenolphthalein indicator • sodium hydroxide solution
• dilute sulfuric acid • 2 pieces of magnesium metal strip
• bromothymol blue indictor • 7 test tubes in test tube rack
• silver nitrate solution • sodium chloride solution
• vinegar • iron(III) chloride solution
• matches • candle
• hotplate • red solution
• water • blue solution
Procedure:
The following procedure will be completed by the lab technician in the video.
1. For each of the following reactions, you will describe the physical characteristics of the initial substances (colour, state of matter, texture, etc.). Note: solutions are described with both their colour and their transparency. So if it is a solution such as water it would be described as colourless (colour) and clear (transparent).
2. Watch the lab technician combine the initial substances as per the instructions.
3. Observe what happens (did you feel heat, see bubbles, hear sound, smell something, etc).
4. Answer any questions.

A. Hydrochloric Acid and Zinc Metal Properties of each of the initial substances:
Place a small piece of zinc metal into a test tube. Then add enough hydrochloric acid to cover the zinc metal to the same test tube. Observations:
B. Water on a Hot Plate Properties of the initial substance:
Place a beaker of water on the hot plate. Turn it on high and bring to a boil.
Observations:
C. Magnesium Metal and Sulfuric Acid Properties of each of the initial substances:
Place a small piece of magnesium metal into a test tube. Then add enough sulfuric acid to cover the magnesium metal to the same test tube. Observations:
Compare A, B, and C. What observation was the same in all three?
Which of these did a chemical change occur, and which was there a physical change?
Explain why seeing a gas does not always indicate that there was a chemical change.
D. Candle Wax and Oxygen Properties of each of the initial substances:
Carefully light the wick of the candle (note that it takes oxygen to cause the candle wax to burn and that the wick can be ignored here). Observations:
Compare C and D. Both reactions had detectable energy released. In what forms were the energy released in each of the reactions?
Were both of these chemical changes? What type of energy changes were they?
E. Sodium Chloride Solution and Silver Nitrate Solution Properties of each of the initial substances:
Place 10 drops of sodium chloride solution and 10 drops of silver nitrate solution into the same test tube. Observations:
F. Iron(III) Chloride Solution and Sodium Hydroxide Solution Properties of each of the initial substances:
Place 10 drops of iron(III) chloride solution and 15 drops of sodium hydroxide into the same test tube. Observations:
Compare E and F. Did a chemical change occur in both? Give evidence (observations) from the lab to support your answer.
G. Sodium Hydroxide Solution and Phenolphthalein Indicator Properties of each of the initial substances:
Place 10 drops of sodium hydroxide solution and 10 drops of phenolphthalein indicator into the same test tube. Observations:
H. Hydrochloric Acid and Bromothymol Blue Indicator Properties of each of the initial substances:
Place 10 drops of hydrochloric acid and 10 drops of bromothymol indicator into the same test tube. Observations:
Properties of each of the initial substances:
Place 10 drops of the red solution and 10 drops of the blue solution into the same test tube. Observations:
Compare G, H, and I. What observation was the same in each of these?
Identify what type of change each of these were, chemical or physical. Explain how you came to this conclusion.