SG Chem 2A Week 8 blog

The past week and a half in SG chemistry has consisted of Labs and also the new concept of equaling out chemical equations. To start the unit we did the nail lab that spanned three days in class as well as a weekend in between. In this lab our purpose was to determine the ratio of copper produced to iron consumed in a replacement reaction. We did this in the separation of copper(II) chloride dihydrate into a solid copper substance, water and chlorine gas. This lab was really great to do at the beginning of the unit so that we could see what we were going to be studying, which is chemical reactions. It also gave me a feel for what a real chemist does in the field, and it is very exciting to see that these reactions are more than just what is on a piece of paper.

The first step in this lab was to take the dehydrated copper(II) chloride and dissolve it in water. It was very cool to observe as it dissolved because it went from green to blue. Something I did not know before this lab was that color change indicates a chemical reaction. I'm curious to discover what kind of reaction it is. We then put iron nails inside the solution and let them sit for overnight. In the photo below you can see how the copper already started condensing around the nails even after first putting them in.

When we came back to class the next day, the solution looked like this.

The copper in the chlorine has separated, with the copper condensing around the iron nails, and the chlorine having evaporated into the air. This leaving mostly water as the liquid. We noticed the liquid was now mostly yellow and I still wonder why all of these color changes took place. We drained the solution leaving the copper behind and rinsed it with deionized water and got what you see below.

What you see below is the copper after it had been dried over the weekend.

After the lab part of this was done it was on to the calculations. After receiving all of our masses and doing the calculations to find the moles of iron and copper we determined that they were at a one to one ratio, and I interpreted this as one atom of iron bonds with one atom of copper.

This lab was very interesting and useful for me because I got to apply what I have been learning the whole trimester. It also really help me visualize the equation and understand what is happening when we write out a chemical reaction. This is especially helped me as we continued into the next concept of balancing equations.

The bulk of the next week was focused on practice in balancing equations. I mostly understood this concept, except what mostly confuses me is when an equation contains polyatomic ions and you have to balance them on each side. I also need more practice with when you have to use mixed fractions and then multiply the entire equation. Aside from this I am good at visualizing the atoms in the equation and understanding what happens in the process.

I really enjoyed the series of labs we did in the middle of the week also. There were 10 different Labs at different stations and we got to experience five different types of reactions; combination reactions, decomposition reactions, single replacement reactions, double replacement reactions and combustion reactions. I again really enjoyed being able to see the chemistry at work because usually we just see it on a piece of paper. I'm looking forward to learning more about these reactions and I'm wondering specifically what these different types of reactions entail, and being able to distinguish them from one another.