On both Wednesday and Thursday, my group preformed a lab on the crystallization of sodium acetate. This lab required that we needed to have background knowledge that we didn't previously know and so was not done by most of our classmates. But for it we crystallized the ionic compound known as sodium acetate, which is one of the products from the reaction between baking soda and vinegar. We mixed together the baking soda and vinegar at a ratio of 28g : 500mL, which produced three things; CO2, H2O, and CH3COONa. The carbon dioxide was released as gas, but we still needed to heat the mixture to get rid of the water. After having rid ourselves of the water, we were left with the sodium acetate, which when allowed to cool formed very awesome crystals throughout the mixture. The whole thing had become solid and crystalline, it was also a very pure white. We still had to drain the leftover liquid and recrystallize though, just to make it as pure as possible. It must've been quite a party on the molecular level, as the mixture cooled down. I suppose the molecules would have come closer together as they lost their thermal energy and formed crystalline structures. As to why they formed those structures particularly, I'm not quite sure, I can only assume it has to do with the mixture being homogeneous. Either way our results were very desirable, due to having very pure crystals. Most of the time the crystals come out yellowish, and I believe that the whiteness of our batch was due to our very precise measurements and patience when it came time to heat the mixture. Although, I will say that they was still some leftover gunk and that I would've preferred if we had left the liquid to heat up a bit more. My partners were Joesph Olmos, and Micah Ohanian. I thought that we worked very well but were a bit distracted at times. In this experiment we could work together in a team, but I fear that our inattentiveness could hinder an experiment in the future. All in all I still feel like our experiment went well and there isn't much I'd change if we had done it again other than leave it heating a little longer to make sure we got rid of as much gunk as possible (if that's the cause). I think I had great partners for this experiment but next time would like to maybe work with some of my other peers to work on future labs. As for the continuation of this lab though, the only way I can see is to try an experiment that some of my other classmates have done in which they add one of the crystals from before when it's still liquid to instantly freeze it. From this lab, I think I took a lot of things away: from how to properly measure things, to experience working with partners on an experiment. One of the more important things I think I learned is how to balance equations and find the mass of molecules/how much is needed in a reaction. There were a couple things that I also solved for in this lab, for example: 1) A mole is a scientific unit of measurement that can be described as a very large amount of a substance. About 6.02 x 10^23 of that substance. 2) The gram ratio between sodium bicarbonate(baking soda) molecules and acetic acid molecules is 7g : 5g (Which means that for every 7g of baking soda used, we must use 5g of acetic acid to make this experiment work.) 3) To get the mole to gram ratio for both NaHCO3 and CH3COOH, we simply find the amu (atomic mass unit) for each element in this molecule. that can be found on the periodic table directly under their names. This unit is how many grams of this element can be found in 1 mole. So, by finding the amu for each element and adding them together, you get the amount of grams that are in one mole of each substance. 4) In Andrew's calculations to find how much baking soda is needed to match the amount of acetic acid used, he had to first divide 25g of acetic acid by 60g(the 25g is because vinegar only has 5% acetic acid so using 500mL of vinegar makes 25g of acetic acid) because as we saw before, 1 mol of acetic acid is 60g. He is converting the grams to moles. We now have .42mol of acetic acid. Next since this is a 1 : 1 ratio (every one molecule of sodium bicarbonate produces one molecule of acetic acid.), we now know that we need .42mol of sodium bicarbonate. And to find that we simply multiply .42 by the amount of grams found in 1 mole of sodium bicarbonate (84g) to get 35g of baking soda. |
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AuthorHello there! I am a sophomore here at High Tech High, and on this blog I will be making weekly posts to what I've been doing in my 10th grade chemistry class! So check back often! Archives
May 2015
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