The purpose of this lab is to determine the concentration of CoCl2 through the precipitate titration of cobalt ions. As seen in the following given equation: CoCl2 (aq) + 2NaOH (aq) → 2NaCl (aq) + Co (OH) 2 (s), the solution comprising of cobalt chloride being titrated with sodium hydroxide causes a double decomposition reaction generating sodium chloride and cobalt hydroxide.
1. The first experiment is Preparation of a Cobalt Amine Bromide Product ; Synthesis #3 was used to create the compound. Added 5 grams of cobalt carbonate to 20 mL of hrdrobromic acid in a beaker. Noticied a slight color change to dark purple. Solution frothed after it settled I mixed in 15mL water and
The wet, crude product was placed into the 50 mL Erlenmeyer flask. Small amounts of CaCl2 were added to dry the solution. The flask was sealed and the mixture was swirled and left to settle. Once
As a group, we obtained our salt mixture of calcium chloride and potassium oxalate, and weighed the mixture. We were able to make an aqueous solution from the mixture and distilled water. We boiled and filtered off the solution, leaving the precipitate. Once the precipitate was dried overnight, it was weighed and the mass was measured. Then we calculated the moles of the precipitate.
(Hint the concentration of calcium ions in well 12 is 4.9 x 10-5 M.) Place 5 drops of 0.10 M NaOH in each of the wells 1 through 12. When the NaOH is added to each well, the initial concentrations of the reactants are halved, as each solution dilutes the other. Use an empty pipet to mix each of these combined solutions by drawing each solution up into the pipet and squirting it back into the well. (Hint the concentration of Ca2 ions in well 12 is 2.4 x 10-5 M.) Allow three or four minutes for the precipitates to form, then observe the pattern of precipitation. At one point the concentration of both ions becomes too low to have any precipitate form. We will assume that the first well with no precipitate represents a saturated solution. Part B NaOH varies, Ca(NO3)2 held constant To check your results, repeat the procedure but use a serial dilution of the NaOH. In a different row, put 5 drops of 0.10-M NaOH in well 1. Put 5 drops of distilled water in wells 2 through 12. Add 5 drops of the 0.10-M NaOH solution to well 2. Use an empty pipet to mix the solution by pulling the solution into the pipet and then squirting it back several times. The solution in this well, 2, is now 0.050 M in OH- ion. Continue this serial dilution to well 12, and then remove 5 drops from well 12. Add 5 drops of 0.10 M Ca(NO3)2 to each of the wells, and mix each with an empty pipet or stirrer. Again, determine the well where no more precipitate appears. Cleanup
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.
We then proceeded in testing for excess Ca2+ by adding two drops of .5 M K2C2O4 to test tube two and attentively observed to see if a precipitate formed, which it did. This meant that Ca2+ was in excess and C2O42- was the limiting reactant in the original salt mixture. We then cleaned up. Upon returning to our next class, we took the filter paper, with the precipitate on it, and took its mass.
In reference to the analysis of anions, Table 1 shows that a precipitate was formed when our unknown was combined with HNO3 and AgNO3, thus indicating the presence of a chloride ion. Because our unknown did not form a precipitate due to HCl and BaCl2, separate, effervesce, or smell, we concluded that neither sulfate, nitrate, carbonate nor
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:-
5. Was there any evidence that some of the copper (II) chloride was left in the beaker? Explain.
Dissolve 2.34 g of cobalt chloride hexahydrate (CoCl2.6H2O) in 100 ml of water in an Erlenmeyer flask. While stirring the oxalic acid solution constantly, add the cobalt chloride solution drop by drop. Let the mixture cool in an ice bath. A precipitate will form slowly.
The reaction characteristics of basic copper carbonate 〖mCuCO〗_3⋅n〖Cu(OH)〗_2 were observed by changing the reaction mole ratio. The reaction mole ratio of sodium carbonate to copper chloride (II) was controlled from 1.08 to 1.68. Fig. 1 shows the XRD patterns of copper carbonate powder. At a reaction ratio of 1.08, paratacamite (Cu_2 Cl(OH)_3 ), beside alkali copper carbonate, was formed because of incomplete reaction at a copper content of 53.9 wt%. Lack of sodium carbonate may cause incomplete reaction with copper chloride (II) because of low pH (6.0) of the solution [12]. The copper content according to the reaction mole ratio were 57.7, 50.5, 58.8, 59.3, and 59.8 wt% at the reaction mole ratios of 1.20, 1.32, 1.44, 1.56, and 1.68, respectively.
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 obtained a composition of 58 (±5.1) wt% Na2CO3 and 42 (±8.3) wt% NaHCO3 for the unknown solid analyzed in this experiment. Although the accuracy of these results cannot be fully evaluated, since we do not have a known composition concentration to compare, we must assume that there was some contribution of error, especially given the somewhat large errors observed. One possible source is a miscalculation of the volumes or concentrations obtained from the results due to exposure of CO2 in our titrants and solutions which, as discussed in the previous lab report, can make our solution more acidic than what the nature of the experiment requires.2 Therefore, different volumes of standard HCl would be necessary for titration. A simple solution for this issue would have been boiling the distilled water to expel carbon dioxide from the stock solutions. Additionally, the stock solutions may also be responsible for some of this error. Besides having stock solutions available for the entire class, which may cause cross contamination and mishandling of the stock solutions, the stock solution needed to be replenished multiple times, thus providing the possibility of preparing a solution with a different molarity. Moreover, at one point all 0.1 M NaOH had been expended, and the only option available was to use a solution of 0.08 M NaOH for further experiments. This was
Co-precipitation is an important technique widely used for separation and pre-concentration of analytes from various samples [examples]. It is adopted when direct precipitation cannot separate the desired metal ions due to their low concentrations in the sample (Bulut VN et al. 2008). Various mechanisms including surface adsorption, ion exchange, surface precipitation and occlusion are involved in co-precipitation technique [ ]. Metals, at trace levels, react with an organic or inorganic compound forming a solid phase. The major precipitate then reacts with other metals to form chelates. Finally, solid particles are separated from the aqueous media and re-dissolved in acid or in an organic solvent (Komjarova I 2 et al. 2006;
The main objective of this experiment is to carry out qualitative analysis to identify metal cations in unknown solution 1.