The objective of this experiment is to synthesize ammonium decavanadate (NH4)6V10O28.6H2O and ammonium trivanadate NH4V3O8 and subsequently determine the water and vanadium content in ammonium decavanadate. Vanadium in the +5 oxidation state forms numerous species in aqueous solution and a tight control of conditions such as pH, temperature and concentration will enable the formation of just the desired species.1 Ammonium decavanadate and ammonium trivanadate will be produced from ammonium metavanadate (NH4VO3) through the careful control of these external conditions.
[...] The volume of 0.05 mL is subtracted from the values in Table 3 and the subtracted volume is used to determine the concentration of KMnO4: Table Corrected Volumes of KMnO4 Used in Calculations Calculating Average Concentrations of KMnO4 Sample Calculation: Volume of KMnO4 = 0.03483 L moles = 0.2476 g = 7.39 x 10-4 moles Molarity = = 0.02122 M KMnO4 The above process was used for the second and third trials Table Concentration of KMnO4 in three different trials Molarity Analysis of Vanadium Content Table Mass of Ammonium Decavanadate and Volumes of KMnO4 Used to Reach Endpoint Mass of Ammonium Volume of Ammonium decavanadate decavanadate Theoretical Weight Percentage of Vanadium Theoretical % = Experimental Weight Percentage of Vanadium Sample Calculation: Moles of VO = 0.0022589 mol VO+ mol VO+2 x Experimental % = x 100% = Table Weight Percentage of Vanadium for two samples Weight Vanadium Percent Error = Table Masses of Ammonium Decavanadate Before and After Dehydration Original Mass New Mass Water Loss Theoretical mass percentage of water Experimental mass percentage of water The percent error is as follows: Discussion The percentage yield of ammonium decavanadate and ammonium trivanadate is and respectively. [...]
[...] The water of hydration of ammonium decavanadate was quantitatively analyzed at with a percentage yield of from the theoretical value of The determination of the Vanadium content in ammonium decavanadate was of the total weight, which is consistent with the theoretical weight percentage of and the whole experiment can be deemed a relatively accurate success. It could have been improved several ways though. A larger number of titrations could have been carried out for the samples so that the random error could be minimized when determining the [...]
[...] The mass of the sample is 0.6043 g after a week, and the difference of 0.02030 g is the mass of the water of hydration. Analysis of Ammonium Vanadates by Manganometry Standardization of KMnO4 A 50mL burette was washed out with distilled water followed by a few ml of 4.5 M H2SO4(aq) and a few ml of approximately 0.02 M KMnO4(aq). A glass funnel was used to fill the burette with KMnO4(aq) and a small amount was run through to ensure no air bubbles were present. [...]
[...] Experimental Synthesis and Analysis of Ammonium Trivanadate and Ammonium Decavanadate A 3.00 g sample of ammonium metavanadate was weighed into a 250mL Erlenmeyer flask and 50mL of distilled water was added. The flask was the heated on gauze using a Bunsen burner for 10 minutes until the entire solid was dissolved. A small amount of undissolved solid that was present was discarded by decanting the solution into a clean flask. The solution turned creamy then yellow initially, but turned a brighter yellow following, heating for 10 minutes. [...]
[...] The phase diagram of vanadium1 shows that ammonium decavanadate was produced in the range pH 4 to pH 6 and log vanadium concentration of 0 to -4. Ammonium trivanadate was produced in the range pH 0 to pH 4 and log vanadium concentration of 0 to 3. This accounts for the synthesis of ammonium decavanadate requiring more acetic acid.1 This experiment proves that by deliberately and quantitatively varying the conditions aforementioned, two different desired ammonium vanadates can be produced. The experimental yield is slightly lower than the theoretical yield for the ammonium decavanadate. [...]
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