In this lab we started out by massing 20mL of water in a 100mL graduated cylinder. We then added BBs until the meniscus went up to 25mL meaning we have 5mL of BBs. We then did 2 more trials and got 10, then 15mL of BBs. After each trial, we then massed the graduated cylinder on the 4 beam balance. After recording the mass and volumes, we were then able to determine the density of our BBs. Since we have 5, 10, and 15mL as our volumes, we must only write the density to the ones place because it was the number in our data with the least amount of significant digits. According to that, our densities were 8, 8, and 8. Looking at our previously researched densities of common metals, I noticed that there was a numerous range of densities from 7.87- 8.9 any of which could be a contributing metal to the BBs. Based on my data, I would have to conclude that the BB consisted of iron with the density of 7.874 because it rounds the closest to my ‘precise’ density of 8. The density supports my conclusion because that is the closest possible answer and or outcome due to the 1 digit density I recorded. My data and calculations are precise because they are all similarly close together. As for accuracy, my data lacks it. Since its measurable data I couldn’t get exact numbers, but if I would have been more precise with my digits when measuring some of my data the results would have been closer to what an actual BB consists of. Densities are different because the equation is Mass/Volume. This means if two things have the same mass, but different volume (which most things do) their densities would differentiate because of that difference in volume.
In this mini lab we explored the conservation of mass? What is the conservation of mass some of you chemistry newbies may ask? The conservation of mass, in its simplest form, states that mass cannot be created nor destroyed. In this lab we had a big beaker, and a small beaker. First we massed both beakers. Then we poured in two fingers of these guys which made the weight of the beaker stand at 148.10 grams where before it was 82.23 grams. Then we filled the little beaker which weighed 29.18 grams, with baking powder that made the new mass of the whole beaker 30.17. This means there was approximately 0.99 grams of baking powder in there. We slowly added the baking powder to the vinegar (slowly so that the fizz didn’t fizz over the entire beaker) and we noticed that a white foam was produced! Now adding the baking powder should have meant that the masses (0.99) of baking powder plus the bigger beaker mass (148.10) should have added up to around 149.09 grams. Consequently, we observed that the mass of the new solution was only 148.66 grams. Wait, the law of conservation says that mass cannot be destroyed… This means that the foam produced a gas of approximately 0.43 grams! This means that matter is conserved in a chemical reaction, but it is changed to a different form. You know this through the calculations you make during the lab that show how much baking soda was turned in to a gas form when added to the vinegar. The gas of the solution is predictable due to the fact that it is dependent on how much baking soda you add to the vinegar because it is that, that is causing the chemical reaction and gas forming in the first place. This would most likely just apply to substances that react with the vinegar (these guys). If there is no chemical reaction between the two, you will not have any gas produced. Now I talked about the calculations that went along with this experiment, but lets go more in depth. We graphed our data and realized that our results fell beneath the line of best fit on our class data chart. This means less gas was produced due to a couple of reasons: We may have added the solids slow causing less of an intense reaction producing less gas, or some of our solid could have stuck to the beaker causing a slight difference in the amount we added. Due to these calculations we figured out for every 1 gram of solid added .4265 grams of gas were produced, this meant that there was a constant slope in the graph making it a linear graph. Just plug in 5 for x to the equation .4256x + .0834 to get 2.21 grams of gas produced. This also means 44 grams of gas are produced for every 84 grams of solid. Now to find out how much gas would be produced for any amount of solid, lets say 5 grams, you just plug 5 in for x in the equation giving you the amount of gas which in this case would be 2.21g. To find out how much solid if 5 grams of gas were produced you simply do the opposite. Plug in 5 to x/.4256+.0834 and you get 11.83! Science is a magical thing! You can also determine a rough estimate of both of these equations by looking at you graph’s axis’ according to the variable you are searching for.
This week we took a test, and also did a mini lab on measurements. I missed school on both Thursday and Friday due to school based activities. I missed a mini lab. Also this week our first glog was due. We are currently learning about chemical formulas and how to name them based on their formulas and vice versa. In the future I will try not to miss that much school, but I do not think that is likely because I will be missing this coming Friday again due to a tennis tournament. I will also try to turn in all my assignments on in time. I honestly think that labs help me understand the material the most because it is a hands on way of learning and it shows you how to do it right and the different effects that will happen if you do things out of order. The UT homework is very tedious, but it helps me realize how much I actually know about the topic at hand which is helpful and reassuring.
In our chemistry mini-lab today, we were basically mixing different chemicals together on a chart and recording their reactions. Some concluded with no observable reaction whereas others turned colors and some even produced precipitants. An example of a precipitant producing mixture was the NaOH and the AgNO. As we mixed these droplets together we noticed a brown clumping in the center of the droplets. As we blew it with air they formed more dense clumps and turned into a solid structure. Our next task on our list was to figure out the chemical name to each compound that we mixed. At first this was easy because it was cations first and then anions. The formulas began to become more complex as subscripts were added which tells you how many of each element there are. To have a correct formula the two ions must be equal which will make the entire thing equal. So if you are given Ag+ and Cl-, the formula would be AgCl because you have both a positive and a negative. The ions are denoted by the subscript tells how many of each element is needed for each other particular compound. In a formula the cation comes first and then the anion because that is a rule of the nomenclature. Patterns in nomenclature deal with the oxyanions. Due to the specific numbers of the element the suffixes will be different.
In the case of Cobalt-60 the type of decay going on is Beta Decay. Which means the isotope is emitting an electron or positron. An example of the equation is shown below.
The half life of the cobalt-60 is 5.27 years which means that it will take approximately 10 half lives for 99% to decay. That’s about 50 years! So where do you run into cobalt-60 radiation? Don’t be frightened people are almost never exposed to cobalt 60. This radiation mainly occurs through radiation beams trying to sanitize in the food industry and through metals like ceramics and so forth. Most interaction with cobalt 60 comes from medical radiation or contaminated food and water. Although when ingested most cobalt 60 leaves through feces, some may be dissolved into tissue. Mainly with this isotope one is unlikely to run into threats unless undergoing a medical treatment. Once a threat has been detected however the person affected will undergo a series of treatments and tests to determine how much had been absorbed and what the best treatment from there will be. Radiation is the natural way an atom or isotope tries to stable and balance itself. With hundred of different isotopes radiation is everywhere so no one can really avoid it completely. Radiation can also be made artificially which is where x-rays and medical treatments come in. Since radiation is natural, like I said no one can 100% avoid it. The atoms nuclei are balancing and undergoing decay. Radiation has been around since the birth of the planet so there’s really nothing humans can do to prevent it.
The model of the atom all begun with a man named John Dalton. HE had the first comprehensive theory of an atom. He stated that matter was composed of invisible particles. The model of this looked a lot like a marble. Following this model, a man named J.J.
Thomson found the negatively charged particle that science now knows as the electron. He found this through experimentation with charged rays. He fired electrical currents through pipes with gas in them. He notice when he recorded the mass that the mass was not changing. From there he concluded that in the pip contained electrically charged particles.
Next, we had the fine discovery of the nucleus which is credited to Ernest Rutherford. He and colleagues shot alpha particles through a sheet of gold foil. By this the observation was that some of the particles went through, but some of them bounced back. They concluded that this heavy part that the particles could not pass through was the dense central part of the atom. Then they named it the nucleus. Next he splits the atom using alpha particles and nitrogen consequently causing him to discover the proton.
In conclusion the model of the atom was empirically developed because these scientists did not have the technology or the knowledge to see the small atom. Technology meaning they could not see it with a microscope or any means they had at their fingertips. They were ignorant to the fact that atoms contained all these individual particles so that is why they did not have to knowledge for discovering these things. Scientist went through blind experimentation, not knowing what they were going to discover, to develop every existent model of the atom. They did not see the atom they used rays, particles and their knowledge of physics to essentially come up with the idea of every individual particle of the atom and diagram what matter consists of. These aspects of the atom were discovered through observation considering they did not have the logic to discover them and that is why it is empirical.
Recently in chemistry we have discussed radioactivity and classifications of matter. We took a test on Tuesday on the classification of matter unit which consisted of homogeneous and heterogeneous substances etc. Later this week we then had a mini lab on the rate of which our dear friend Frosty the Snowman melted. This taught us about the linear relationships of graphs and that data pools help scientists have more precise data collections and answers. We also did a lab about radioactivity and half lives that used the candy skittles. This helped me learn that you cannot predict the exact time an atom will decay but you can make an educated guess. Next the class is planning on going further into the study of radioactivity. I think this will be interesting because it will deal with the elements individual since no characteristics of these elements are the same.