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!