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 (150-250 ml)
copper(II) sulfate pentahydrate - be careful it will kill you !!
100 ml 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 or demonstration of terms and concepts with have recently learned in lecture. Thus, as you read and follow the procedure, being 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 you lab station after taking all appropriate saftey 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 to 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.

Question: Make one qualitative and two  quantitative observations of a physical property of the water in the space below. Be sure to clearly distinguish which is which. 

•  There was about 97 ml of water in our beaker~quantitative.
• We put only one big scoop of cupric sulfate pentahydrate.~quantitative.
• There is no smell to it~qualitative.

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. Place the CuSO45H20 in the beaker, and stir withe the stirring rod until all the solid has dissolved. 

Question:You have just made a mixture of CUSO4 in water. is the mixture heterogeneous or homogeneous? Explain.

Homogeneous mixture because it is completely uniform throughout the mixture.

Obtain the aluminum foil sample in front of you and crumple it into a loose ball. place the aluminum ball into t he copper(II) sulfate solution, and stir gently for about 15 sec. Write down detailed observations of everything you see in the space below: At least one of the observations should be quantitative.

OBSERVATIONS AFTER ADDITION OF THE ALUMINUM:

The aluminum isn't doing anything at the moment and we thought it was a heterogeneous mixture.

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

No there was on chemical change just physical change at the time.

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 the sodium chloride is dissolved and make detailed observations of everything you see in the space below: Again, at least one of the observations should be quantitative. 

***P.S. DON'T let the sodium chloride touch your skin it will start to burn off!!! Just joking its just  regular table salt. :) 

OBSERVATIONS AFTER ADDITION OF SODIUM CHLORIDE:

The mixture started bubbling and turning the aluminum foil a rusty kind of color. It also went up 3 degrees when we added the sodium chloride to it.

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

We saw a chemical change. There was all four of the chemical change indicators when we added it.

(if you are wondering what the indicators are they are at the bottom of this page)

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?

4 states of matter:

• The mixture~homogeneous.
• The aluminum in the mixture~heterogeneous.
• Aluminum the element~compound.
• The element~formed.

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

Cu+Al2(SO4)3 Our group guessed copper.

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 a 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.

DISCUSSION: 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. From the discussion in the class, list the indicators below:

INDICATORS OF CHEMICAL CHANGE

1. Bubbling(without adding heat)
2. Change in color
3. Formation of precipitation
4. Change in temperature 

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