Science 8 Laboratory Experiment
OBSERVING CHEMICAL CHANGES
PURPOSE: To observe a chemical reaction and record the evidence for any chemical changes observed.
- 2 - 100 mL beakers
- distilled water
- stirring rod
- small scoopful of copper(II) chloride
- paper towel
- 10 cm x 10 cm square of aluminum foil
- mortar and pestle
Note: All your observations must be written into an “OBSERVATIONS” section.
1. Pour about 40 mL of distilled water into a 100 mL beaker.
2. Place one scoop of copper(II) chloride into a second 100 mL beaker. Describe the copper(II) chloride.
3. Without stirring, drop the copper(II) chloride into the water in the first beaker. Look at the chemical in the water, from the side, and describe what you see for a minute.
4. Use a stirring rod to stir the solid copper(II) chloride in the water for a minute. Describe what you see. Take the temperature of the solution and record this as the “Initial Temperature”.
5. Make a loose ball out of the aluminum foil —DO NOT SCRUNCH IT UP TIGHT!! Describe the aluminum foil.
6. Drop the aluminum foil into the copper(II) chloride solution. Use the thermometer to CAREFULLY STIR THE MIXTURE. CARE: THE THERMOMETER CAN BE BROKEN EASILY WHEN USED LIKE THIS SO BE VERY CAREFUL NOT TO BUMP THE THERMOMETER AGAINST THE BEAKER! Describe everything you see, including any changes in temperature.
7. When no more changes are observed, carefully pour the liquid into the sink and use a stirring rod to dump the remaining solid in the beaker onto a piece of dry paper towel, in a little pile. Carefully fold the paper towel over the pile of solid and squeeze the solid until it is dry. You may have to use different places on the paper towel to get the solid dry. Describe the dried solid.
8. Place the dry pile of solid in a mortar and pestle and use the pestle (fat-ended rod) to firmly grind the solid into the bottom of the mortar (bowl). After one minute look at the solid and describe what you see. (Check with your teacher to make sure you have done everything correctly.)
9. Dispose of the solid in the garbage, clean your equipment and put it back where you found it.
1. What physical change(s) occurred during this experiment?
2. Make a list of the chemical changes you observed and the evidence you have to support each statement.
3. Where do you think the aluminum foil went?
4. When copper is chemically reacted, the solid metal dissolves and forms a blue solution. What evidence do you have that dissolved copper is or is not left in solution at the end of your reaction?
5. What do you think the red solid was? What evidence do you have to support this conclusion?
6. Is it possible that the bubbles were caused by boiling and not by a chemical change? Explain.