SG Chemistry 2A Week 2 Blog

           This week in Chemistry our main focus was scientists and their discoveries in history, a topic I found very interesting to learn about. But before we dove into this, we started the week finishing up and white boarding the last three problems on Unit 4 worksheet 2, which was on Avogadro's hypothesis. 
            Before we went over these problems in class I was very confused by the concept that two volumes of hydrogen chloride were formed from only one volume of hydrogen and chlorine.  The rest of my table was too, so when we displayed our answer we had 6 molecules of hydrogen (having only one atom) and 6 molecules of chlorine (containing 2 atoms) that when combined only had 3 molecules of hydrogen chlorine in each volume, just like shown below.

            We quickly learned, after looking around the room, that there was something not right about this answer. Dr.Finnan showed us that this violates the conservation of mass law.  We then realized that hydrogen must contain 2 atoms in order for this to honor the conservation of mass law as well as Avogadro's hypothesis. When showing our answers for the next question, where two volumes of nitric oxide combined with one volume of oxygen to form two volumes of a reddish-brown gas, we took this knowledge and applied it so that the number of molecules in each volume were equal.

          Transitioning into famous scientists and their discoveries in history we began watching a movie that followed the lives of scientists Antoine Lavoisier and Joseph Priestley. I found this movie was much more interesting than other documentaries because instead of other people talking about Lavoisier's and Priestley's discoveries, there were actors to play the scientists and reenact their experiments. This made it much easier to visualize and with actual lines spoken from the scientist's journals I found it was more realistic.

           The video’s main concept was centered around the discovery of air and oxygen as well as elements and what they are.  Joseph Priestley noticed that when Mercury Calx, a red solid stone, was heated it did more than just turn into mercury, a silver liquid metal, but emit a strange gas also.  He did many experiments with this gas. He collected it and lit a flame in it, observing that it burned much longer and brighter than in normal air, and he also put mice into this gas and regular air and the mouse in this new gas lived much longer. Lavoisier later named this gas oxygen and after conducting an experiment burning a flame in a mixture of oxygen and phlogiston he came to rename phlogiston hydrogen.

           Learning about the way oxygen, the most essential gas for life, and hydrogen were discovered is so exciting to me, and getting to conduct the experiments in Dalton’s playhouse online that these famous scientists also did is very cool.  Online we did three experiments, the mercury calx experiment done by Priestley, the flame experiment done by Lavoisier and the burning of diamonds and coal experiment and recorded our findings.  These interactive experiments really helped me to understand these concepts on a deeper level doing them myself. I really enjoyed learning about the history of chemistry, knowing the background will make my learning much more applied and in depth.

SG Chemistry 2A Week 1 blog

Chemistry 2 Week 1 blog

This week in SG Chemistry 2A we began to dive deeper in to the classifications of matter. Early in the week we learned the differences between atoms, elements, pure substances, mixtures and compounds. An atom is a single particle of an element, and the element is what categorizes and consist of only one type of atom.  When all the particles in a substance are identical, the substance is pure. If the substance contains different types of particles, it is a mixture. Both elements and compounds are defined as pure substances, only a compound contains two or more elements which are linked together by chemical bonds.  We also distinguished that mixtures can be separated by physical means while compounds can only be separated by a chemical reaction. This idea lead us to a demonstration where we watched Dr.Finnan separate water (H2O) into 2 units of Hydrogen and 1 unit of Oxygen (demonstrating the separation of compounds by breaking chemical bonds). We then did a worksheet that asked us about the means of mixture separation (as shown below). 

As we continued to learn about atoms and mixtures on our own, we also came together as a class to display what we've learned on white boards.  We first established some white board norms together, these included that we must always have a key to show which atoms represent which elements, always use more than one atom to represent an element, and that arrows represent movement. We demonstrated these rules in our display of Dr.Finnan's sugar in water and ethanol lab. In this lab he used three beakers each filled with a different substance, one with water, one with ethanol, and one with half water and half ethanol.  He then put one sugar cube in each beaker and we observed how the sugar dissolved.  The sugar dissolved in water, but not at all in ethanol, and only half way in the half-and-half beaker.  This was very interesting, I did not know that sugar didn't dissolve in ethanol. We then displayed our observation on white boards as tables, showing the before and afters of the sugar cubes. Below is my table's display: 

We also walked around the room with sticky notes and were able to give each other helpful tips and comments. This really allowed my table to see what we needed to improve on and also get some encouraging feedback.

We watched another video of a scientist performing lab demonstrations in which he was separating compounds and mixtures by both chemical and physical means. At the end of the video he came to the conclusion that if the same amount of gases are at the same temperature and pressure, then the number of particles must be the same. This is known as Avogadro's Hypothesis.

The Unit 4 Worksheet 2 that we worked on explored Avogadro's hypothesis more.  The worksheet contained problems in which we had to draw the combinations of elements. We also displayed our answers for this worksheet on white boards, and Avogadro's Hypothesis concluded our chemistry learning for the week.