Mar. 25-28

This week, I learned more about what when elements combine to form substances.

For the most part, the charges of the elements were consistent and unchanging. But, I realized that wasn't the case with transition metals. Transition metals, depending on the charges of the other elements they combine with to form an ionic compound, can alter its charge.

During the beginning of the lab, CuCl was an ionic compound. Cl in CuCl has a charge of -1, hence Cu must have a charge of +1.

This is what I learned in the copper chloride lab. The objective was to see what would happen if water and copper chloride chemically combined together.

I hypothesized that when they combined, the copper would stay the same since it is a metal while chlorine, hydrogen, and oxygen are gases. To combine them together, we used the electrolysis equipment. My group and I filled the trough with 100 mL of water and 4 g of copper chloride.As the copper chloride was combined with the water, the water turned blue. I concluded this was the case because the copper oxidized as the CuCl bonded with H2O.

But, if H2^2 charge + O^-2 charge + Cu^X charge + Cl^-1 charge combined, then how would they form an ionic compound? In order for the ionic compound to be neutral, the charge of copper would have to be +1. However, I noticed that at the bottom of the trough, there was oxidized copper. While the CuCl combined with water, the oxygen separated the copper while the H2 separated the chlorine. As the separation between the two occurred, the copper was oxidized by the oxygen atom in the process.

But, what would copper's charge be if it combined with oxygen? Knowing that copper is a conductive positively charged metal and knowing that oxygen has a charge of -2, copper combined with oxygen must have a charge of +2. In this case, then how would the chlorine combine with the H2O. Already knowing that H2O is an ionic compound already, it wouldn't make sense for it to combine with chlorine. Therefore, the copper and the chlorine were separated from each other as the copper chloride was combined with water.

Because the CuCl dissolved in water, I concluded that the CuCl ions became polarized, hence interrupting intermolecular forces and phase changes. If this were the case, then I wonder if factors, such as melting point and freezing point would be different from CuCl and just copper and chlorine. If this would be true, then the attraction between the particles would change. I think that as copper and chloride were separated from the water, the attraction between the CuCl ions and the H2O ions was less than that of the attraction between copper and chloride atoms.

Knowing that single elements regain their charge once separated from ionic compounds, I concluded this is what happened to chlorine and copper. Knowing that chlorine gain the electrons that copper lost, chlorine would become more positive while the copper became more negative.

This week, I also participated in the electroscope lab, which pertains to charge induction. I made my electroscope using aluminum, a glass jar, and a plastic lid taped to the glass jar. To make the electroscope, I poked a hole in the middle of the ball and stuck the rod through it so the ball wouldn't fall off of the rod. Then I poked a hole in the plastic lid and stuck the rod through the hole. Then, I bent the bottom at a 90º angle and attached the unwrinkled and even-length aluminum leaves.

Then, I tapped the rod to the plastic lid and then taped the lid on the glass charge.

To test the conductivity of my electroscope, I rubbed a balloon against my shirt to charge the balloon. As soon as I held the balloon over the aluminum ball, electrostatic electricity took place in the aluminum rod. I almost made the mistake that the electrons were being transferred from the balloon to the aluminum. But, as soon as I differentiated between that and chemically combined substances, I then realized that the polarity was only being affected, not the number of electrons between the balloon and the aluminum.

Since the aluminum itself was neutrally charged just as the balloon was, charge induction occurred. The negative charges in the aluminum were only being shifted as the balloon was brought near it. Knowing that the electrical current passed through the rod, I concluded that it must have passed through the leaves at the bottom. Since the polarity was shifted, I figured that the negatives and positives were being evenly shifted together toward the leaves.