Week 33

This week in Chem, we didn't learn much of anything new. In the beginning of the week, we did an assessment that was the same one we did in the beginning of the year. It didn't count for a grade or anything but just something to see how we progressed. Some of the concepts I was a little shaky on but I think I did pretty well overall. Then, we did the silver coke bottle lab. It wasn't a very difficult lab, but needed to be followed exactly. First we all got to drink our pops, I didn't get a coke though:(. Then, we put 10 mL of dextrose into the bottle and sealed it with a rubber stopper. In a beaker, we put 40mL of silver nitrate in and added drops of ammonia. The solution turned brown, and formed a brown precipitate, but we kept adding drops until it was clear again. Next, we added 15 mL of potassium hydroxide into the solution of silver nitrate, and again added drops of ammonia until it was clear. I actually added 50mL of potassium hydroxide to my solution, but the product still came out great. So, we carefully poured the the mixture into our bottles, put on the stopper, and began to shake it, making sure we covered the entire inside of the bottle. After a while, the solution began to form that silver lining on the inside of the bottle and you couldn't see through it. So once you couldn't see through, we carefully poured the mixture down the drain, rinsed the bottle, and left it there upside down to dry. We didn't get to take home the bottle until the next week though. When the seniors were taking their exams, we broke off into groups and used the standards for the past few units to make a PowerPoint study guide. We finished these study guides in class and can use them to study for our final. I'm very nervous for our final and will have to prepare very much to make sure I'm ready by the time we take it.

Week 32

In Week 32 of Chem, we brought up our experiment from last week to go more in-depth. We noticed that during the reaction, the temperature of the test tube increased, meaning that energy left the system. This brought us back to the LOL diagrams. We now have another means of storage for energy: chemical. We incorporated the new storage account into our LOL diagrams for further examinations. So, we continued the studying of energy in these reactions. We found that when energy exits the system, making the energy of products greater than the energy of the reactants, it's exothermic. However, when energy enters a system for a reaction, making the energy of products greater than the energy of reactants, it's called endothermic. We continued to examine an experiment from a while ago when we electrolyzed copper chloride, yielding copper and chloride. Because the charge on the copper is 2+, it needs 2 electrons to make copper neutral. This loss of electrons is called oxidation. However, the 2 chloride ions have two extra electrons that they need to lose to become neutral. This gain of electrons is called reduction. These reactions together are considered coupled reactions. Electrolyzing this solution was considered a chemical electrical circuit, like a battery is. Next we moved to thermodynamics and worked with The First Law of Thermodynamics. Internal energy is the total amount of all the potential and kinetic energy that a system has. The First Law of Thermodynamics states that the change in internal energy of a system equals the sum of the heat and work. Mr. Abud won teacher of the year so wasn't able to be with us for the last two days of the week, so I will have many questions based on what we learned next week.

Week 30

Week 30 was more continued studying of stoichiometry.  Monday we all tried each other's cookies that we made over the weekend.  Each of us had a different recipe that ended up having either too much, or too little of a certain ingredient.  These fluctuating amounts created disgusting cookies, except for one group's that were perfect.  One of the cookies had way too much salt, some had too much flour, and a few other different amounts of ingredients.  This cookie experiment relates to equations and balancing.  If the proportions are not exact, the result will not end up being what was planned.  There has to be the correct amount of each element to react properly with others.  As we continued the week, we continued with stoichiometry.  We really focused on the importance of proportions to predict the products that would be yielded in a reaction.  With these proportions, we also focused on the limiting and excess reactants in the reaction.  Depending on which reactant was in excess or limited would play a major role in the products.  We also learned about percent yielded, which is the percent of products yielded compared to the theoretical amount that could result from the reaction.  I feel very confident with the assessment we took at the end of the week since I really grasped the concept.

Week 29

It seems as though we did not make much progress in the 29th week of chemistry.  The week was slow, and continued to base our work around proportions.  In the beginning of the week, we ran through a bunch of different experiments, like burning magnesium, mixing lead nitrate and sodium iodide, putting aluminum foil in copper sulfate, and a few more.  The purpose of these experiments, though, was to learn more about the proportions.  The results of the reactions we caused wouldn't have happened if it weren't for us having the correct proportions of reactants.  With this increased work with proportions, we returned to our work with moles.  This work, however, came in a different format.  We now use moles with BCA Tables.  BCA stands for Before Change After.  We use these tables to track the transfer of moles of atoms of each element in a reaction.  We can also predict how much of one element with be used or produced based on the proportions in the equation.  This process of measuring chemical reactions is referred to as stoichiometry.  What we've done so far is just the beginning of stoichiometry and we will continue our work with it in days to come.  Before our assessment for the week, Mr. Abud proved to us in one more experiment the importance of proportions.  In a large water jug, he put ethanol in and swirled it around.  He then lit a match and dropped it in, causing the ethanol to ignite for a quick moment.  Then, he put in more ethanol than the first trial, and tried dropping in the match again, except there was only a flame at the top of the jug.  This is because there was not enough oxygen in the jug to react with the ethanol and create the same effect as the first trial.  Our assessment covered balancing an equation, and then making a BCA table to predict an outcome of a reaction.  I'm sure our study of stoichiometry will grow into much larger concepts.