Intro to Chemistry Lab

Purpose:

        To become familiar with the laboratory and to make qualitative and quantitative observations about physical and chemical changes during a chemical reaction.

Materials:

Beaker

Copper(II) sulfate pentahydrate - caution, toxic substance

Scoopula

100ml graduated cylinder

Stirring rod

Thermometer

Small Square of Aluminum Foil

Procedure:

        This lab is unique in that it serves both as an introduction to both the laboratory environment and as a review and demonstration of terms and concepts we have recently learned in lecture. Thus, as you read and follow the procedure, be sure to answer all questions that are posed to you in the space provided.

        First, form a lab group of two or three people. Go to your lab station after taking all appropriate safety precautions we have discussed in the safety lecture. (You MUST wear safety goggles and apron)

        You will find in front of you a beaker (150 or 250 ml), a 100 ml graduated cylinder, a scoopula, a thermometer, some aluminum foil, and a container holding some cupric sulfate pentahydrate. Go to the appropriate source and add some water in your beaker. The exact amount is not important, although it should be between 75 and 100 ml.

        Make one qualitative and two quantitative observations of a physical property of the water. Be sure to distinguish which is which.

        Now, using the scoopula, obtain some of the copper(II) sulfate pentahydrate. Again the exact amount is unimportant, but your scoopula should be about one quarter filled with the solid (ask if you have any questions). Place the CuSO45H2O in the beaker, and stir with the stirring rod until all the solid has dissolved.

        Obtain the aluminum foil sample in front of you and crumple it into a loose ball. Place the aluminum ball into the copper(II) sulfate solution, and stir gently for about 15 sec. 

        Write down detailed observations of everything you see. One of them should be a quantitative.
        Make sure your scoopula is clean (rinse with tap water and dry with a paper towel if not) and obtain a large scoop of sodium chloride from the labeled container. Add the NaCl to the beaker containing the copper(H) sulfate - aluminum mixture. Stir until all of the sodium chloride is dissolved.

        Write down detailed observations. At least one needs to be a quantitative.

        After approximately 10 minutes, take your beaker over to the large funnel and beaker and slowly decant (pour) your mixture into the beaker. The instructor will show you a way to do this that will insure that all the liquid ends up in the funnel. Then clean your beaker thoroughly with soap and tap water, and then final rinse with distilled water. Make sure your lab station is clean, return all safety equipment to its proper location, and return to your desk.

Hypothesis:
        We hypothesized that the mixture would eat away the aluminum foil.

Data:
        Nothing happened until you add the NaCl to your mixture and it begins to rust away the aluminum tin foil until it rusts to nothing but rust.

Lab Discussion:

        Did a chemical change occur after the addition of the aluminum? Explain.

        Did you just see a physical change or a chemical change? Explain.

        How many different states of matter do you observe? Describe, from your observations, what they are. Which do you see in the beaker right now?

        Any idea what the red solid is that has dropped to the bottom of the beaker?

        You have just observed a chemical reaction between copper ion and aluminum, which produced copper metal, hydrogen gas, and aluminum ions. During the course of the reaction, you should have made several different observations that are all indicators that a chemical change is occurring.

Conclusion:
        Our hypothesis was that the mixture would eat away the aluminum foil. It did but it turned into rust. Creating a new substance making a chemical change.

Indicators of Chemical Change

1. Formation of a Participate
2. Heat Transfer 
3. Color Change
4. Bubbles without heat