Week 17

In the beginning of the week, we had a few educators from around the state come in and watch our class. They took videos and pictures of us and how we use technology in the classroom. The day that they were there, we were trying to figure out the percentage of water in a can of Pepsi. So we basically took a 100mL sample and distilled it. Unfortunately though, we didn't wait long enough for all the water to come out of it and when massing the Pepsi, we made some errors so it ruined the result. We couldn't accurately measure amount of water that came out. That day, we also learned what a colloid was. A colloid is a mixture in between a suspension and a solution. One that will not unmix by itself but is partially dissolved. We continued discussion about mixtures and compounds and the differences between the two. This took us to the concept of fixed ratios. The ratios of atoms in a mixture do not matter, while they do in a compound. If the ratios weren't the same in compounds then it wouldn't be the same molecule. From there, we moved to nomenclature. Nomenclature is the naming system for chemical compounds. There are a few rules we have to stick by like when there's only one atom of the first element, there's no need to say "mono" before. Rules such as this allow us to name compounds that we don't already know the name of. Also, there are two main classes of elements: metals and nonmetals. When naming two nonmetals, you need a prefix but with metals and nonmetals, you don't. Then we learned that there are some elements that are diatomic, which means they come in pairs. We finished the week learning that volume of a gas and number of particles is proportional. We have midterms coming up, and I'm extremely nervous for them. We'll see how it goes.

Week 16

In week 16 we started off finishing unit 3 then started unit 4. To finish unit 3, we came to some conclusions about the ice cream lab. When we did the lab, the arrangement of the ice particles was disrupted by the salt and changed. The salt raised the phase energy of the ice, then some thermal energy was transferred to the phase account of the ice as well. The cream then replenished the thermal energy of the ice, dropping the temperature and therefore producing ice cream! This then took us to two new concepts. Freezing point depression, which is the lowering of a freezing point of a substance by affecting phase energy. Also boiling point elevation, which is raising the boiling point of a substance by affecting phase energy. However I still do not understand the significance of these two concepts, but will find out this week. So then began unit 4. To start off the week, we did a small lab to introduce some new ideas. We were given a mixture of iron fillings, sand, seeds and salt that we had to separate. Starting off, we poured the mixture onto the table. Using a magnet to glide over the mixture, the iron fillings would attract and separate from the rest of the mixture. Next we put filter paper into a funnel and poured water and the mixture into a beaker. The mixture and water was then poured into the funnel, and the water would continue through the funnel into another beaker. The salt dissolved into the water when it was poured in, and would go into the other beaker through the funnel along with the water. The bird seed would be trapped on the filter paper, and once we took out the paper it could be easily separated. The sand stayed at the bottom of the beaker when we were pouring the water, and once all the water was gone the sand could simply be taken out of the beaker. All that was left was the salt dissolved in the water. To make things simple and working with our limited time, we left a small amount of water in a small dish overnight. When we came back the next day, the water was evaporated and salt was left in the dish. This lab started us off with learning about mixtures, compounds, and elements. A mixture is made of atoms and has a combination of two or more shared properties. Mixtures can also be separated based on physical properties. Compounds, though, are made of molecules and have different kinds of atoms. They can be separated based on chemical properties. Elements are made up of one type of atom. This upcoming week I'll try and further my understanding of these as the end of 1st semester approaches!

Week 15

Week 15 was one of the most fun weeks we've had in Chem so far this year. The week was composed of our soap projects and making ice cream. For the soap, we each brought in supplies and made Evernote presentations for the projects. We needed stuff like soap bases, fragrances, food coloring and some sort of mold. When making the soap, we used a melt and pour method. We melted the soap base until completely melted in a beaker on a hot plate, then mixed in fragrances and coloring. We stirred it and finally poured it into the molds and let them cool over night. Simple as that! Each group presented their projects acting as a company with a logo and history. It was a very cool, simple, and fun project to do. The ice cream making was a surprise on our last day before break. Using simple ingredients like ice, salt, vanilla, milk, sugar, and whipping cream, we easily made vanilla ice cream. In the gallon zip lock bag, we put in ice and salt. Then on the inside of that bag went a quart size zip lock bag filled with the rest of the ingredients. Making sure both bags were tightly sealed, we shook the bags for about 10 minutes to get the finished product. Unfortunately, though, we didn't have enough time for ice cream, but still ended up with a delicious milkshake! Week 15 in Chem was a great way to begin our Christmas Break.