Week 4 Blog

Ariana Trossen

SG Chem 2

Dr. Finnan

10/10/15

     This week in class we continued to discover how to count particles. First, we ratio of masses of chicken eggs and quail eggs. Then, we looked at Avogadro's number, 6.022×10²³, which is a mole. After that, we began to calculate the number of moles in something and how one mole compares to other large numbers of things, such as cells in the human body. To further our understanding of counting particles, we did an experiment of reactions with zinc chloride to determine the empirical formula. We learned about Tare Weight next and how it helps us determine the mass of contents in a bottle. For homework this weekend we got a worksheet to help us to continue to practicing calculating the moles, atoms, and molecules in different objects and compounds. Before looking at Avogadro's number, we looked at the masses of chicken and quail egg samples.

     A standard chicken egg has a mass of 37.44g and a standard quail egg has a mass of 2.34g. From this we were able to determine that the ratio of masses between chicken and quail eggs is 16:1. Then, we compared larger samples of chicken and quail eggs, such as 10 eggs, 438, 1 dozen, and 1 million, In each scenario we found that the ratio of their masses is always 16:1. Using this information, we compared the masses of elements instead and found the same thing; the ratio of masses of two different elements, no matter how many atoms are in each sample, as long as they're the same, will always have the same ratio. Knowing this information makes it possible for us to find the the number of atoms in two samples of elements and find the masses of samples of elements. This also helped us begin to understand what a mole is.

     A mole is 6.022×10²³ particles, this is also known as Avogadro' s number. A mole is so big that you can't even count that high. To really understand how large a mole is, we compared it to the number of cells in the body of every human on earth. We found that mole is still greater than that. It is important to compare and understand ratios between samples and elements because it helps us to determine the relationships between them. We experimented on zinc to find out how it reacted with chlorine and their relationship.

     This lab we did was called the Empirical Formula Lab. In this experiment we put zinc and hydrochloric acid together. From this we were supposed to find the empirical formula of zinc chloride, a product of the reaction between zinc and hydrochloric acid. Empirical means "based on experimental evidence." Based on our experimental evidence we found that the empirical formula for zinc chloride is ZnCl2. We determined this by calculating masses and determining the number of moles of zinc and chlorine. By finding the ratio of the moles of chlorine and zinc and it equaled approximately 2, so the ratio of moles of chlorine to zinc is 2:1. After looking at how zinc and chlorine compare in zinc chloride, we moved on to look at sample containers of different elements and compounds to calculate the number of atoms, molecules, and moles.

     In class we were given multiple different bottles that contained different elements and compounds. Our worksheet asked us questions about how many atoms, or how many molecules, or how many moles were in each bottle. However, in order to find these things we needed to subtract the mass of the bottle from the mass of the bottle plus the element or compound inside. The mass of the bottle itself is known as the Tare Weight (T.W.).  Once we found the individual element or compound mass we could continue to calculate the moles, atoms, or molecules. To do this you have to know that the atomic number of each elements is equivalent to one mole of that element. If you are given a sample of an element, you can determine the portion of a mole that the sample equals. Each group in our class was assigned a specific problem to white board out, we were assigned problem #7. In this problem we were asked to find the number of atoms in a bottle of iron nails. In order to do this, we found the mass of the bottle plus the iron nails. Then, we subtracted the T.W. from the total mass, which gave of the mass of the iron nails. After that, we divided the mass of the iron nails by the atomic mass of iron. We then took that number and multiplied it by Avogadro's number, 6.022×10²³, and this gave us the answer of how many atoms were in the sample of iron nails.

     To end the week we were given a worksheet for extra practice on calculating the moles, atoms, and molecules. I am glad we got this worksheet. I feel the more practice I get with these problems, the better I am at solving them. However, I still don't feel 100% sure about all of them yet. I still struggle sometimes with knowing what numbers to divide or multiply by what. Ultimately, I feel I am getting better.