Gravimetry is an old technique which has been used for the determination and recovery of gold ever since its discovery. It is a process that has a minimal room for instrumental error and does not require standards for any calculation of the unknown that is being analyzed. The determination of gold besides gravimetry can either be titrimetry or instrumental, but these techniques requires gold standards for comparison of its results and concerns the determination of gold in small scale or trace amounts like that of atomic absorption spectroscopy (AAS). The demand for gold is rapidly icreasing world wide and as of today, the standard test for its determination is Fire Assay ASTM E 1335-08 – a method that requires expertise, time, and can lead to a decrease in the sample’s amount. In this study, Gold – a rare metal known for its worth, value, and properties such as conductivity, malleability, and high reflective power was determime by proposing a new gravimetric method through gold’s reduction by hydroxylamine hydrochloride as an alternative to the standard test method called the fire assay. The researchers based all their calculations using an ISO standard guideline, EURACHEM/GUM. Gold samples with five replicates of approximately 0.2g was carried out by acid digestion using a solution containing 15mL of 35% Hydrochloric acid and 5mL of 69% of nitric acid in the presence of 10mL de-ionized 18.2M Ω resistivity water of analytical grade per sample. Samples were weighed using
The empirical formula for silver oxide for trial one is Ag5O4 and for trial two is Ag3O2. For trial one there is 0.451 grams of silver were produced from 0.504 grams of silver oxide. For trial two there is 0.456 grams of silver were produced from 0.500 grams of silver oxide. The difference between the mass of silver oxide and mass of silver is the mass of oxygen that vaporized into the air. There are 0.053 grams of oxygen vaporized into the air for trial one and 0.456 grams’ oxygen for trial two.
In the hood, place the copper wire in 10mL of nitric acid and wait for it to dissolve. Afterwards, add 100mL of deionized water to the solution and boil the solution, so all the nitrogen oxides are removed. Place the solution to a 250.0mL volumetric flask and add deionized water to the flask until the solution is 250.0mL. When the solution in the flask is at 250.0mL place the solution in a clean plastic bottle. Now cut a penny into four pieces, and measure the mass of all the pieces together. Go back to the hood, and place the pieces of the penny into a 250mL beaker. Afterwards, add 20mL of concentrated hydrochloric acid. Wait for the hydrochloric acid to dissolve the zinc core. When the zinc has dissolved, filter the solution through the filter paper, and place the copper metal pieces into a clean 150mL beaker. In the hood, place 4mL of concentrated nitric acid in the beaker, and when the copper dissolves add, one drop at a time, 30mL of 6 M ammonium hydroxide to neutralize the nitric acid. Transfer the copper/ammonia solution to a 100.00mL volumetric flask. Prepare four different calibration
2. Obtained a 2-3 cm strip of magnesium metal ribbon and coiled it loosely into a small ball. Added the magnesium metal to the acid in the test tube.
The objectives of this lab was to determine the density of pennies minted in different years. Then to compare the densities of those pennies to see what change or changes occurred in the composition of the pennies. And finally, to try to identify possible metals in the cores of the pennies.
Then next way that we determined the hardness of water was through Atomic Absorption spectrophotometry (AA). The way that this hardness is determined
To begin the procedure of the gravimetric analysis of chloride, 0.501g of Amine (C8H9NO) was weighed on an analytical balance and added to a 10mL volumetric flask. At this point 5mL of deionized water was added to dissolve the Amine. Then 5mL of 1 M AgNO3, which was already combined with 4 M HNO3, is added to the 10mL volumetric flask and stirred. To collect the AgCl precipitate,
0.1 gram of my product from the second trial was weighed in a tray and was then added to a fourth test tube containing 2.0 mL of Iron (III) chloride, which was measured using a 10 mL graduated cylinder, to test for
The purpose of this experiment was to determine the pKa, Ka, and molar mass of an unknown acid (#14). The pKa was found to be 3.88, the Ka was found to be 1.318 x 10 -4, and the molar mass was found to be 171.9 g/mol.
In the blank cuvettes, the 2 mL of pH levels 2,5,7, and 10 were added first, followed by the 1mL of peroxidase. However our experimental cuvettes contained both hydrogen peroxide and guaiacol. Before the cuvettes were placed in the spectrophotometer we added 0.1 mL of H202, followed by 0.02 mL of guaiacol these two substances were added last immediately before they were placed in the spectrophotometer. Para film was placed over the cuvette opening, and the assay solution was shaken and placed into the spectrophotometer where its saturation level was then tested. We recorded the saturation level of the solution every 15 seconds for 3 minutes. This process was repeated two times for each pH level for a total of two trials.
To begin Lab 7 of Chem 115, a clean and dry porcelain crucible and its cover were obtained. Next, an iron ring was attached to a ring stand. A clay triangle was placed on top to the ring and a Bunsen burner was placed under the ring. Following the setup for the experiment, the crucible and its cover were placed on the clay triangle and were heated for about five minutes. After, the burner was turned off and the crucible and cover were left to cool to room temperature. Once the crucible and its cover had reached room temperature, tongs were used to move them to a wire gauze. Using the wire guaze, the crucible and its cover were transported to an analytical scale to weigh and record the mass of it. Next, a strip of magnesium was obtained and
AAS has contributed to the understanding of elements having different absorption emission spectra due to their difference in energy levels. In the absorption spectrum, the absorbed light are shown as black gaps. As the number of electrons increase, the number of spectral lines also increase. Hence, by measuring the absorption of light, the concentration of the element within a sample can be determined. By knowing the concentrations of an element, scientists are now aware that even the smallest amount can make a significant impact towards the biological system. Therefore, scientists have brainstormed ways to monitor the use of chemicals in the
One milliliter of 6.00-M phosphoric acid was placed into a 125-mL Erlenmeyer flask using a volumetric pipette. Using a slightly larger pipette, six milliliters of 3.00-M sodium hydroxide was transferred into a 50-mL beaker. Then a disposable pipette was used to slowly mix the sodium hydroxide into the phosphoric acid while the solution was swirled around. Then both the beaker and flask were rinsed with 2-mL of deionized water and set aside. A clean and dry evaporating dish was weighed with watch glass on a scale. Then the solution was poured into the dish and the watch glass was placed on top. The solution was then heated with a Bunsen burner to allow for the water to boil off to reveal a dry white solid. After the dish cooled to room temperature it was once again weighed and the new mass was recorded.
For my Senior Project, I am submitting a lab which I completed in AP Chemistry. In the Gravimetric Analysis of Calcium and Hard Water Lab my lab partner and I conducted an experiment in which we calculated the mass of the precipitate formed by the mass of the isolated analyte present in the reactants before the reaction. During our experiment, we used resources such as graduated cylinders, sodium carbonate, bunsen burners, an analytical balance, watch glass, filter paper, a funnel, tongs, and an oven. The lab equipment allowed us to effectively precise measurements of water hardness. For example, the analytical balance gave us a more precise measurement than a triple beam balance would. The temperature of the burners as well as the temperature
I am writing to you today because I am in need of funding for an extraordinary new experiment that could change chemistry forever. My new experiment is called the Gold Foil Experiment that should prove that the atom is mostly empty space and that electrons revolve in circular orbits around a substantial positive charge in the center. This experiment will disprove what was previously believed about the atom. It will disprove the plum pudding model by JJ Thompson, which presents the atom as a huge sphere of positive charge with scattered negative charges. The Gold Foil Experiment will show the world that this is false and that the atom is actually mainly empty space with a positively charged center.