Determination of Copper(Ii) Concentration by Spectrophotometry

In six different 50mL volumetric flasks there was 0.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, and 10.00mL of the 5.00 g/L Cu^(2+)stock solution. 3mL of 15M ammonia was added into each flask, once the ammonia was added each flask was diluted with water to 50 mL then were all thoroughly mixed.

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.

Discussion of Results and Scientific Explanations: The goal of this laboratory was learn how to use the Spectrophotometer to analyze the phosphate content in colas. This is important because the consumers believe that the buffering capacity of phosphate within the colas will settle their upset stomachs.  A spectrophotometer, or Spec 20, measures how much a chemical substance absorbs and transmits. The next goal is to determine the relationship between absorbance and transmittance.  Transmittance is a measurement of the amount of light that passes through a substance.

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.

-If the copper metal is submerged in the silver nitrate solution then in reaction, a pure, solid (Ag) silver product is created with an excess of (Cu (NO3)2) copper (II) aqueous liquid because a single displacement reaction occurs where the balance equation is then

A spectrophotometer is an instrument which measures the amount of light of a specified wavelength which passes through a medium. This instrument is usually used for the measurement of reflectance of solutions. Light is separate into different wavelengths and is being passed through the sample solution. The sample solution will have its own wavelength and will absorb a certain amount of light. The higher the molecular concentration, the higher the absorbance value.

The lab performed required the use of quantitative and analytical analysis along with limiting reagent analysis. The reaction of Copper (II) Sulfate, CuSO4, mass of 7.0015g with 2.0095g Fe or iron powder produced a solid precipitate of copper while the solution remained the blue color. Through this the appropriate reaction had to be determined out of the two possibilities. Through the use of a vacuum filtration system the mass of Cu was found to be 2.1726g which meant that through limiting reagent analysis Fe was determined to be the limiting reagent and the chemical reaction was determined to be as following:-

The Copper Cycle is a popular experiment used to determine if an element, in this instance, copper, reverts to its elemental form after a chain of reactions. This experiment is very dangerous because of the reactions between the strong acids and bases. In this experiment I performed a series of reactions starting with copper metal and nitric acid to form copper (II) nitrate. Then I reacted copper and several other solutions such as, sodium hydroxide, sulfuric acid, ammonium hydroxide, and hydrochloric acid to form precipitates. In conclusion my percent recovery

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

Incorporation of assay controls included setting up a spectrophotomer and running the chart recorder with a full-scale deflection before the start of the assay. The set recorder had a corresponding value of 1 for the change in the absorbance. Therefore, prior testing was done to observe whether a change occurred in the readings. This helped to indicate that the results were valid, as they could have been affected by a fault during the setting up of the spectrophotometer. On the other hand this was considered as one of the controls for the experiment. Nevertheless, a new cuvette had to be used for each assay.

After this, the solution was poured into a volumetric flask just about to the 1dm3 line and then it was left there to cool to the same temperature as the room before filling precisely to the 1dm3 line with distilled water. The molar mass of CuSO4.5H20 was 249.5 so that means 249.5g of copper sulphate was needed to dissolve, in order to make a standard solution, into 1dm3of distilled water. Following this, a linear dilution of the CuSO4.5H2O was made in order to be used to make a calibration curve after using the colorimeter to write down the absorbance of each sample. A linear dilution is diluted with distilled water in order for it to make the concentration weaker and weaker. For this investigation, the dilutions made ranged from 0.01 to 0.1 M/l . It was essential to only make up 10cm3

concentration, record the absorbance readings at a fixed wavelength, and plot the absorbance vs. concentration data. The wavelength of 520 nm was selected for experiment Part

Before the synthesis of the Copper Iodine Compound, the identities provided (CuNO3)2 and Nal weighed 1.65 g and 4.7 g, respectively. After being weighed, the (CuNO3)2 exhibited a blue color, while the Nal, through observation, was a white color. However, when both identities were combined, the product turned into a brown and red rocky material. Once 20 mL of deionized water was added, the product quickly turned pale pink paste. After the solution was repeatedly washed with a total of an additional 100 mL of deionized water, the product was powdery and pink with small grains, and was left to air-dry. Once the product was air dried, it was observed to be a pale pink color, while the filter paper was stiff as the product was hard and dry. Therefore, the solid was scraped off onto a recrystallizing dish. However, the mass of an empty recrystallizing dish needed to be recorded in order to compare how much of the synthesized copper iodide was obtained. Within this case, the empty recrystallizing dish used weighed 32.01 g, the product on the empty dish weighed 1.03 g, having a total weight of 33.04 g.

A spectrophotometer’s purpose is to use colors of the light spectrum to determine the concentration of light absorbing molecules in a solution. (p.59) In this particular lab, our mission was to determine the protein concentration and the standard curve of the unknown sample of BSA. This, by preparing five dilutions of the unknown solution of BSA together with other known concentrations, and then experimenting by observing how the concentrations were passed through the spectrophotometer. The outcome resolved in the absorption levels being decreased, and this

8) Steps 1 - 8 were repeated using the wavelengths of 360 nm to 900