Cobalt Calorimetry Lab Report

In the fume hood, 3 mL of a 15 M concentrated ammonia solution was added to each volumetric flask. The flasks were swirled until all solids were dissolved. Each flask was diluted to volume with distilled water, covered with Parafilm, and mixed. The concentration (in g/L) of Cu2+ was calculated in each of the six standard solutions.

From this graph and chart we can see that the higher the concentration the higher the absorbance, all the different concentrations were tested at the same wavelength (625nm). Also we can determine our unknown substances concentration by using the absorbance we got for it. The red dot on the graph followed by the line towards the horizontal axis indicates that the concentration of fast green was 34% or 5.1x10-3.

3ml of sample was taken first flask at 4 minutes and added to the appropriate tube of sodium hydroxide, from the second flask at 4.5 minute and so on, each flask was sampled at 30 second intervals. The sampling was then repeated starting at 8,12,16 minutes. The final sample from the last flask was taken at 18.5 minutes. Once the sampling was completed, measurements of absorbance were obtained for solution in each tube at 405 nm.

In this task the concentration of an unknown sample of copper sulphate using colorimetry was used to find the concentration. In this investigation copper sulphate was used which is CuSO4.5H20 as a formula. To make a standard solution which was 1M, the same clean equipment was used to make up the standard solution as used to make sodium carbonate. However there was one difference and that was that the hot distilled water was used to dissolve the copper sulphate crystals. There had to be enough hot water in order to dissolve the crystals into the beaker and then add cold distilled water to cool the solution.

We kept the volume at a constant 0.50 L and first set up the moles to 1.00 moles. The molarity of Co(NO3)2 was 2.00 mol/L. When we decreased the number of solute moles to 0.50 moles, the molarity of the solution was 1.00 mol/L. The quantitative data was collected and we concluded that the relationship between the number of solute moles and the molarity of the solution was direct for the reason that whenever the the moles increased, the molarity increased. However, when the moles decreased the molarity decreases as well. We then combined the two relationships to conclude that the derived unit for molarity is the number of moles/volume of the solution. We believe our claim is right because it was not opinion based. Our theory is proven by facts and that is the simple reason. To conclude, our claim is that the relationships consist of the following: number of moles of the solute is directly proportionate to the molarity of the solution; the volume of the solution is inversely proportionate to the molarity of the solution; and that the derived units for the molarity are number of moles of the solute per the volume of the

Time) because it had a correlation closest to 1. All three orders were graphed and a linear regression was used to see which graphed order was closest to 1. The order was determined by comparing the concentration and time to the mathematical predictions made using the integrated rate laws. Analyzing each graph and finding each correlation helped determine which graph was closest to 1. The more concentrated a solution is, the higher the absorbance of that solution. This is due to Beer’s Law. The law measures the absorbance of a solution by determining how much light passes through a solution. As the concentration of a solution increases, fewer wavelengths of light are able to pass through the concentrated solution. The absorbance at 60 seconds was 0.573 (Figure 1: Table1). To calculate the concentration (molarity), the Beer’s Law equation was used, Abs = slope(m)+b. Plugging in what is known into the Beer’s Law equation resulted in 0.573 = 3.172e+004 + 0, where the concentration is determined by M = 0.573-0/ 3.172e+004. So, the concentration at 60 seconds using the equation (M = 0.573-0 / 3.172e+004) was 1.824e-5 M. The 1st order graph resulted in k=0.006152 (Figure 1: Graph 1). Other groups also resulted in their decolorization of CV to be the 1st rate

Scientists use an instrument called a spectrometer to quantitatively determine the amount of light absorbed by a solution. The primary inner parts of a typical spectrometer are described below. The spectrometer has a light source that emits white light containing a vast mixture of different wavelengths of electromagnetic radiation. The wavelength of interest is then selected using a monochromator (“mono” meaning one and “chromate” meaning color) and an additional exit slit. The separation of white light into different colors (wavelengths) is known as diffraction. The selected light then reaches the sample and depending on how the light interacts with the chemical compound of interest, some of the light is absorbed and some passes straight through. By comparing the amount of light entering the sample (P0) with the amount of light reaching the detector (P), the spectrometer is able to tell how much light is absorbed by the sample.

The purpose of this lab was to determine the percent cobalt and oxalate by mass, and with that information, the empirical formula for cobalt oxalate hydrate, using the general formula Coa(C2O4)b.cH2O.

This experiment was design to find the amount of copper in a penny using a visible spectroscopy. We achieved this by combining .89 to .93 of Cu(NO3)2*2.5H2O to a 25mL volumetric flask and filling the flask to about half full with deionized water, swirl, then fill to the line with more deionized water. After, fill a 25mL burret with Cu2+ stock, with this add .5, 1, 1.5, and 2 mL of the stock to four different volumetric flask, add 2mL of 15 M NH3 from the burret to each flask and swirl, then fill to the line with deionized water. First, calibrate the spectrophotometer then; enter samples of each of the four samples in the spectrophotometer to test the absorbency. For the penny stock solution, use a 500 mL filter flask with about 250 mL of 1 M NaOH, place a rubber stopper to the top and connect a inverted long stem funnel to it using tygon tubing, and place a 125 mL flask below it. Turn on the water aspirator, place the penny in the 125 mL flask, measure out 20-25 mL of 8 M nitric acid in a 50 mL graduated cylinder, and then slowly add it. It should take about 5-10 minutes for the penny to dissolve.

XIV. Record your observations of the dried, cooled copper metal and weigh the recovered copper.

A spectrophotometer is an instrument that is used to measure how much light an object absorbs, each object will absorb and reflect light differently providing us with a different measurement each time (Foist 2013). In this case I measured the absorbance of each cuvette; the absorbance was measured in a range value of 0.0 to 1.0. Elements are best

Apparatus: Spectrophotometer (UV-1201), cuvettes, water bath (set at 37°C), 200µl and 1000µl micropipettes and test tube

In this experiment, two reactions were run to determine the molar absorptivity and the equilibrium constant of FeSCN2+. The main principles used in this lab are equilibrium, LeChatlier’s Principle, Beer’s Law and Spectrocopy. The first reaction was run to completion using LeChatier’s Principle and the second reaction was run to equilibrium. A spectrophotometer was used to measure absorbances. Using a graph of absorbance versus concentration of FeSCN2+ was used to determine that the molar absorptivity constant was 3670. Beer’s Law was used to determine that the average equilibrium constant was 33.1793.

The purpose of the experiment was to find the absorbance value and T% of cobalt (II) nitrate solutions at various wavelengths. Using Beer’s law to determine the concentration of an unknown cobalt (II) nitrate solution with the %T and A values of the known Cobalt (II) nitrate concentrations.

The element cobalt was discovered by Swedish chemist Georg Brandt in 1730. Cobalt had been unknowingly used in pottery for centuries, but Brandt published his scientific results about the metal in 1739. The blue color given off when cobalt is used in pottery was originally thought to be because of another element, bismuth; Georg proved this wrong. At first there were speculations of whether or not that this was a new element. Some other scientists claimed it was just a compound of iron and arsenic. Eventually it gained the recognition it deserved as an element.