Chemistry 2A Week 4 Review

     This week in chemistry most of what we did revolved around the mole. At first, many, including myself, had a hard time understanding what a mole was. But, through worksheets and continuous setup of conversions, I discovered the mole is simply a number. 6.02E23. I can have a mole of pencils if I have 6.02E23 pencils. I can have a mole of chicken wings if I had 6.02E23 chicken wings. A mole is just a number.

     On Monday we completed the Relative Mass and the Mole worksheet. By comparing chicken and quail eggs we slowly began to figure out what a mole was. I remember early on in the week I struggled with this concept. I kept making the problems more complicated than what they had to be. Dr. Finnan taught us the conversion method. We used this on many of our worksheets including the extension to the Relative mass and the Mole worksheet. The conversion method makes finding moles a lot easier.

     Example of conversion method

     On Tuesday we continued to learn about the mole with the Chemistry Unit 5-The Mole worksheet. The worksheet gave us nice examples of moles so we could grasp the concept of the mole as a number. For example, if we had a mole of rice grains, all the land area of the earth would be covered with rice to a depth of about 75 meters. The class continued to practice the conversion method with this worksheet and I myself understood the mole a lot better after Tuesday's work.

     On Wednesday we began the Empirical Formula Lab. First we received a beaker and we measured the beaker. We then added zinc and measured the mass of the beaker and zinc. After we found both weights using the scales, we added about 50 mL of  3M HCl. The beaker began bubbling and fizzing. We then put our beakers under the hood and waited until Thursday so we could see what had happened to our zinc.

     On Thursday, we continued the Empirical Formula Lab. We took our beakers back from under the hood and measured the mass of the beaker and its contents again. The mass had gone up compared to Wednesday's measurement. We then burned the zinc chloride. While burning, a funny smell was produced and the color of zinc chloride went from white to brown. We then measure the mass of the beaker and its contents again and found a slight decrease in mass compared to the measurement we took before burning it. After all the measuring, we completed the back side of the worksheet and found the empirical formula for zinc chloride to be ZnCl2. This makes sense to me because from our calculations, we know there are about twice as many moles of Cl than moles of Zn.

Empirical Formula Lab Class Data

 

 

Burning of the zinc chloride

Table 5 having fun in Chemistry 2A!!

 



 

     On Friday the class finished a good week of moles with the Unit 5 Worksheet 2 in class and homework. The in class part went alright. I don't think the entire class understands the concept of the mole. There were problems when the class was white-boarding that didn't really make sense. Some groups did a good job and some didn't.

    As for me, I have a pretty solid concept of the mole and the conversion method of calculations. The one part I don't really understand is when a problem asks you to find the number of atoms of a specific element in a compound. Like number 9 on the homework. I might be making it too complicated but I hope to clarify it next week in class. My participation was pretty good overall. I could definitely be more focused in class. Other than that I look forward to another exciting week in Chemistry 2A.