Week 1 Blog

Ariana Trossen
5th hour SG Chem 2
Dr. Finnan

This week in class we reviewed classification of matter and techniques for separating compounds and mixtures, and we learned some new information, such as, Avogadro's hypothesis. While reviewing classification of matter, we looked at the difference between atoms, particles, and molecules. Atoms are the individual building blocks of particles and molecules. A particle is any single atom or multiple atoms chemically bonded together. A molecule is two or more atoms chemically bonded together. We went further after this to compare pure substances, mixtures, elements, and compounds. A pure substance is any combination of a single type of atom or molecule. A mixture is a combination of different types of atoms and/or molecules. Elements are combinations of a single type of atom, they can be individual or chemically bonded together. A compound is a combination of different types of atoms chemically bonded together. All elements and compounds are pure substances. Compounds and mixtures can be separated, but not in the same ways. Mixtures can be separated physically, such as with a magnet or by filtering, but compounds have to be separated by chemical means because there are chemical bonds to hold the atoms together, ways to do this include electrolysis and decomposition. We went on to learn about Avogadro's hypothesis, which states that with two given samples of an ideal gas, of the same volume and at the same temperature and pressure, contain the same number of molecules. This makes it possible to find the formulas of compounds formed when gases react.226 In some cases we found that in order to keep the mass the same the molecules of some gaseous elements have to have two atoms. An example of this is when hydrogen and chlorine react to form hydrogen chloride.

An experiment we did in class was with sugar cubes to see how they would react when placed in water, ethanol, and a 50/50 mix of water and ethanol.

https://www.evernote.com/shard/s83/share/eee0-s83/res/d06e68b0-e06d-48a6-955a-9dd572f7a0e9/dissolvingSugarClass.mp4 (video link of experiment)

In this experiment we discovered that the sugar cube dissolves completely in water, not at all in ethanol, and not quite completely in the 50/50 mix and also at a slower rate than in pure water. After doing the experiment we white boarded out particle drawings of the before and after for the sugar cube placed in water and the sugar cube placed in ethanol.

All these things we learned this week are connected. We started from the beginning with the basics of how matter is classified. Atoms are the building blocks of molecules and both an atom and a molecule are considered particles. Then we have atoms and molecules that make up pure substances, mixtures, elements, or compounds. A mixture is different molecules and/or atoms mixed together. A pure substance is any single type of atom or molecule. An element is any atom or molecule made up of a single type of atom. A compound is any type of molecule made up of different atoms chemically bonded together. Elements and compounds are both pure substances. Then we expanded by talking about how compounds and mixtures are separated. Compounds have to be separated by chemical means, which we were showed in the experiment of separating water molecules. This also proved that water is made up of two hydrogens and one oxygen. Mixtures, however can be separated by physical means, which we were showed when a magnet was used to separate iron from a mixture with sulfur. Avogadro's hypothesis ties into this as we learned to draw out the formulas for how elements react and form compounds with particle drawings. I feel we learned a lot this week and am excited to further my knowledge and understanding of chemistry.