Chemistry Entry 4

Mole fact.

Continuing into what we started the previous week, this week our class delved further into Unit 5. The first thing we covered was the topic of Relative Mass and the Mole, and how we could use them to count atoms by using just a balance. I was familiar with relative mass, but a mole was an entirely new concept for me, that I am still trying to understand as we progress further into using this measurement. A mole is the mass of a substance (in the case of the worksheet; oxygen and sulfur) containing the same number of fundamental units as there are atoms, in the specific number of 6.022 x 10e23. The units of a mole can range anywhere from a molecule to an atom, but they always have the same number. This number is called Avogadro's number, with Avogadro being a famous scientist we discussed about in Unit 4. Back to the worksheet, we were given a table of oxygen and sulfur atoms, and needed to find the mass of the sample, through knowing the number of atoms in that sample. This could be found through multiplying the mass of the first sample (contains one atom), by the number of atoms in each column. Once this was completed, we made a ratio between the oxygen and sulfur atoms, comparing the number and masses of the atoms. Our table came to the conclusion that, the ratio of the sample masses will be equal to the ratio of the atom's masses. We also realized that, by knowing the relative masses of the above elements, you can use them to "count" atoms, with the quantity being the mole. As the unit Mole can be confusing and  add complexity to an "average" question, the next day we burrowed deeper into this enormous number. To give somebody an idea of how massive a mole is, 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.

Heating up the substances.

Post heating.

In addition to the problems we solved regarding the unit mole, last week we did a lab called the "Empirical Formula Lab", empirical meaning based on previous experimental evidence.  In this experiment, a specific amount of zinc was mixed with hydrochloric acid. With our table groups, we had to collect data that would enable us to determine the empirical formula of zinc chloride (Zn?Cl?).  This lab took two days to complete, as the reactants needed a specified amount of time to combine. On day 1, all we had to do was find the mass of a regular, empty beaker, and then add zinc pieces to find the mass of both the zinc and bottle. Once this was complete, we had to add 3 moles of hydrochloric acid, so we could place the beaker in a safe location so as to finish the rest of the lab the next day. Picking up where we had left off, day 2 was slightly more complex, for me at least. recording the observations in day 1 just involved us to examine and interpret what was occurring, but day 2 required a little more calculation. Our workplace was set up to enable us to heat the beaker, so as to remove the unneeded water from the zinc chloride. Our only restriction was to remove the heated beaker immediately off the bunsen burner, if the contents began smoking. Once the zinc chloride was finished heating, it was interesting to see how it solidifies from its molten state. Once this process was complete, the mass of the beaker and zinc chloride had to be found twice. The idea of measuring it twice was to verify that the second mass is lighter than the first (by approximately .02 grams).

White boarding of question 8.

Finishing up the week, as a class we white boarded a worksheet involving problems with sealed sample containers. We had to find the mass of said containers as well as of its contents. A new vocabulary word I learned from this was Tare Weight. Tare weight is the containers empty mass, and is helpful as the number is needed for various calculations throughout the sheet. The questions varied, but the main idea of this was to learn how to find the number of moles or atoms in a container, given a formula. The formula of the contents is incredibly useful as you need to multiply the number of atoms in the formula, by their respected average atomic numbers, so you can plug it into the main equation once all the values are found. I found this week slightly confusing due to the mole, but also intriguing as you can apply the mole multiple chemistry concepts, which helps me to understand them more.

Naturally, I enjoyed the below demonstration you gave for our class.

I took a video and then screen shotted this!