In another mini lab, we were conducting the experiment of trying to find the thickness of aluminum foil and the thickness of the aluminum foil in my group was 1.85 mm^3.I figured this out by using the density (mass/volume), the mass, the area of the foil, and by using conversions to solve for the thickness. The mass I used was .5 g, my group decided to cut out a square that was 10 cm by 10 cm, though when we remeasured it, it came out to 9.98 cm by 9.99 cm, which gave us an area of around 10,000 mm^2. The mass we found the square to be was 0.185 grams. Through many conversions we were able to come up with the result of 1.85 mm^3, this is reliable because we were able to find the correct density, volume, mass and area and we also calculated our masses and lengths to the best of our ability, so my group would say that 1.85 mm^3 is known as our foil’s thickness and is considered very accurate and reliable.
Today, we performed an exploration mini lab in which we attempted to find the composition of BB’s in a container through precision and accuracy. We began by taking a 100 mL graduated cylinder and filling it with 20 mL of water; then we found the mass of it on a balancing scale. We also found the mass of the graduated cylinder with 20 mL of water and with a volume of BB’s equal to 5 mL, 10 mL, and 15 mL. To get the final masses of the BB’s we subtracted the mass of the cylinder and water.
My groups results:
- 20mL of water+G.C.+5 mL BB’s=99.55g
- 20mL of water+G.C.+10 mL BB’s=139.55g
- 20mL of water+G.C.+15 mL BB’s=161.85g
The mass of each:
- 5 mL BB’s: 38.9g
- 10 mL BB’s: 78.95g
- 15 mL BB’s: 101.25g
Density of each:
- 5mL BB’s: 7.78 g/cm3
- 10 mL BB’s: 7.895 g/cm3
- 15 mL BB’s: 6.75 g/cm3
From this data, I can draw the conclusion that the BB’s are composed of Copper and Zinc. Copper has a density of 8.933 g/cm3 and zinc has a density of 7.134 g/cm3. These two averaged together to form a density of 8.0335 g/cm3, which is close to the average density from my experiment. My groups data is pretty reliable, but could have been more if we would have used the rules of significant digits. On our scale, we had the ability to measure to the 1/100th place, therefore, we had the ability to guess the 1/1000th place. We only took our data to the 1/100th place. This is a lack of precision. For example how a number such as 161.85 is not equal to and is less precise than 161.850, and that a greater number of zeros at the end of a number with a decimal means greater precision.
Today in class we performed a lab that was based off the law of conservation which states that matter can not be created or destroyed. We were given two beakers, one small and one big, the small one was to have anywhere between .5g to 1.25g of an unknown powder while the big one had two fingers of an unknown liquid. We were to record the mass of the beakers without the substances and we had to known how much of each substance we used. Then we massed the beakers with the correct substance in each beaker; after that we combined the powder into the liquid to watch the reaction take place. It immediately began to bubble and fizz as it turned a milky white color on top. During the chemical reaction it produced a gas which created a smaller mass than the original two components. Then after the reaction had begun to settle, we massed the beakers again. What we were looking for was the amount of gas produced; if you have more powder you will produce more gas and the less powder the less gas produced. In the lab there was a predictable relationship because you could add up the liquid and solid and subtract it by the final mass after the reaction and it would give you the amount of gas released.Matter is conserved in a chemical reaction because when adding up the amounts of each substance and the final mass of the mixture it is proven that the only matter lost was gas. In my group, our point was considered good but it had a higher gas produced than average since it was over the best fit line so it could have been better.When figuring the amount of gas that is released we got 44/88 grams of gas should be produced during the reaction in this lab. There were two ways to find how much gas was produced and one way was calculating and graphing the line of best fit and then finding the slope according to all of the results from each group. Our best fit line we got y=.4256x+.0834 which concluded that for every 1 gram of solid, you get .4265g of gas that is produced. Another way you can figure out the gas is setting up the chemical equation for this lab which is NaHCO3+HCH3COO=NaCH3COO+CO2+H2O which resulted in the mass of CO2 being 44 and the mass of the solid was 84. If .5g of a solid is used you can solve how much gas was produced by taking (44/84)x and plugging 5 into the x to get the answer or you could multiply .4256 by 5 to come up with how much gas was produced as well. The answer is 2.128 grams of gas would be produced and the answer to how much of the solid was used is .08512.; you solve this by dividing .4256 by 5 or the second way is by dividing 44/84 by 5.
Today in chemistry, we completed an ion exploration mini lab. Basically, we were provided a laminated chart and were to mix different chemicals and then record each reaction. Many reactions occurred, some had no noticeable changes while other changed colors and produced new substances. An example of the color change was the mixture of Pb2+ and the KI, this mixture cause the two chemicals to result in a bright yellow color and had an almost paint like appearance. We mixed each chemicals with a blower (pipette) that could mix together both chemicals without having to actually touch the substances or the chart. After we completed gathering all our data, we had to figure out the chemical name to each compound we had created. The cations are the positive ions and the anions are the negative ions; the cations always come first before the anions when figuring the chemical name. For example, Ag+ and I- has one negative and one positive charge therefore the charges cancel out to zero and becomes AgI. These first mixtures of the chemicals were extremely easy to figure out because they were simple but soon they started to get more difficult like Fe3+ and CO 2 over 3-. You had to actually think and remember everything we had been learning about subscripts and charges which can mess up your chemical name if you do not complete it correctly. The subscripts are known as how many of each element is needed for each particular substance and compound.
An atom is known as a fundamental piece of matter. Everything in the universe is made of matter, so, everything in the universe is made of atoms. An atom itself is made up of three kinds of particles called: protons, neutrons, and electrons. The protons and the neutrons make up the center of the atom called the nucleus and the electrons fly around above the nucleus in a small cloud. How do we know all of this? Did we use microscopes to look inside an atom? To answer this there is no “atomic microscope” which would allow one to look inside an atom and say how many protons, electrons and neutrons are inside. The way the structure of the atom was devised was through a long series of experiments. Each one was designed to look at a specific aspect of the atom. At one time the atom was thought to be a solid ball of positive charge with electrons embedded in it. Then in 1909, Ernest Rutherford did an experiment which demonstrated that that idea was wrong and that the positive charge was centered at the center of the atom and occupied a very small volume compared to the whole atom. Before the neutron was discovered in 1932, the nucleus was thought to have both protons and electrons in it. The number of protons was chosen to get the correct atomic weight and the number of electrons was chosen to get the correct nuclear charge. It turned out that this model did not give predictions that agreed with experiment. The discovery of the neutron lead to a revision of the model leading to the current one.In the current model, the number of electrons in the atom is determined by gamma and x-ray spectroscopy. The number of protons in the atom is chosen to balance the charge of the electrons in the atom. The number of neutrons in the atom is chosen to give the correct atomic weight for the element in question. Many additional experiments were performed to confirm the model and the mutual agreement between the experimental results and the predictions based on the model is what is called proof.
Cesium is a soft, silvery white-gray metal that occurs in nature as cesium-133. Cesium 133 is an isotope of cesium used especially in atomic clocks and one of whose atomic transitions is used as a scientific time standard and exists as a naturally stable isotope. It has 9,192,631,770 electron cycles per second and isn’t considered radioactive. This is a stable fission product produced from power plants; even though radiation is not a problem from Cesium 133, there are many other isotopes that emit radiation that is harmful to humans and nature. It’s natural so it can be found in nature and is not harmful in low doses! Cesium can even be taken into the body by eating food, drinking water, or breathing air. After being taken in, cesium behaves in a manner similar to potassium and distributes uniformly throughout the body. Radioactivity is found in nature and comes from many elements. Every day, we ingest and inhale radioactive elements in our air and food and the water. Natural radioactivity is common in the rocks and soil that makes up our planet, in water and oceans, and in our building materials and homes. There is nowhere on Earth that you can not find Natural Radioactivity.
Frosty was melting at a rate of .45 mL every minute. We believe that Frosty met his demise at 9:21 which is 58 minutes before we actually began the lab; we had 24 mL of water in the graduated cylinder when we began this mini lab. After we collected our data we were able to graph and find the equation of the line, including the slope which was the rate Frosty melted at.The line of this graph was mostly linear because it had a steady increase almost the entire time.
In our Skittles Radioactive Decay Lab, we had to collect 80 skittles and place them in a cup, from there we would shake the cup and spill them out onto a flat surface. We separated out the ones with the “s” side down, which represented atoms that decayed, until there were no more left.
Once the class had finished with their experiments, we came together and wrote down all our results so we could calculate the class average for each toss (half-lives). Then each group graphed their own data radioactive nuclei per toss.When graphing our data, it formed an exponential graph, which is a downward curve as the half-lives continued. This is different from Frosty’s graph, which formed a linear graph that had a slope that increased steadily.