Abstract This paper describes the methods used in the identification, investigation of properties, and synthesis of an unknown compound. The compound was identified as calcium nitrate by a variety of tests. When the compound was received, it was already known to be one of twelve possible ionic compounds. The flame test identified the presence of the calcium anion in the compound. The compound tested positive for the nitrate cation using the iron sulfate test. At this point it was hypothesized that the compound was calcium nitrate. Reactivity tests and quantitative analysis comparing the unknown compound with calcium nitrate supported this hypothesis. Synthesis reactions were then carried out and analyzed. Introduction …show more content…
Once the quantitative analysis indicated that the compound had been correctly identified, it was also our goal to determine methods of synthesizing the compound and to compare the syntheses for cost effectiveness, safety, and potential yield. Discussion The unknown ionic compound was composed of translucent crystals. It had no odor, was soluble in water, and its electrical conductivity in water was measured at 1.66V, as indicated in Table 1. The compound burned a bright red during the flame test consistent with the flame signature of calcium, as indicated in Table 2, and along with the fact that the compound was soluble in water, this helped us to eliminate the possible presence of the poorly soluble salts (Cooper, 2008). However, tests for these anions were still performed. The compound was tested for the presence of ammonium, carbonate, sulfate, chloride, and nitrate, as seen in Table 2. The nitrate test produced a precipitate, indicating the presence of the nitrate ion in the compound. At this point it was hypothesized that our unknown compound was calcium nitrate. In order to test the hypothesis, the same tests given in Table 1 and Table 2 were performed on a sample of calcium nitrate. The results obtained for all the tests were the same as with our unknown compound. To further test this hypothesis, five different reactions were designed, as can be seen in Table 3, in which a
Reaction 3- 1. Obtained a clean and dry test tube and placed a small amount ( about the size of a jelly bean) of ammonium carbonate into the test tube.
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 Experiment B the limiting reactant was determined to be CaCl2 when two drops of the test reagent 0.5 M CaCl2 was added to the supernatant liquid in test tube 1, and a precipitate formed. Since there was a reaction, there was C2O42- in excess and Ca2+ is the limiting reactant in the original salt mixture present in test tube 1 . This was further confirmed when two drops of the test reagent .05M K2C2O4 was added to the supernatant liquid in test tube 2. There was no precipitate because Ca2+ was not present since it was the limiting reactant and instead C2O42- was in excess.
Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.
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
In conclusion, this lab was a failure. Not only was the yield very small upon inspection, but the product’s composition was unknown due to the unknown solution. Given the nature of the lab, little yield was expected and observed, making the lab itself very particular in nature. Add to this the addition of the unknown solution and any produce was astounding. Not only unfortunate, the unknown solution was very dangerous. If it had been some solution that reacted violently with the reagents, there could have been unforeseen damage done to the lab and the individuals
In a chemistry stockroom, a vial of an Unknown White Compound was found. In order to properly dispose of the substance, the substance has to be identified .The possible compounds has been limited to one of 15 different compounds. Also, approximately 5 grams of the Unknown White Compound (UWC) were available for testing. In order to determine the properties of the compound, a series of tests was conducted. These tests included a ph test, a conductivity test, a flame test, a sulfate test, a halide test, an ammonium test, a solubility test, and a carbonate test. Using the results of these experiments, it was hypothesized that the UWC is potassium chloride. To further confirm the hypothesis, a synthesis of potassium chloride was conducted.
Unknown white compound (823U) was discovered in the lab. In order to dispose of it correctly, the substance and its physical and chemical properties had to be identified. The unknown white compound was one of a list of 15 compounds. 5g of the unknown compound were given in order to correctly identify and discover its physical and chemical properties. In order to do so, a solubility test, a flame test, and ion tests were conducted. From the results of these initial tests and the given list of compounds, the unknown white compound was thought to be composed of sodium and a halide (I-, Br-, or Cl-). Of the list, NaCl was the appropriate compound, however NaC2H3O3 was also tested out of skepticism. To verify the identity of the substance, the solubility and flame tests were performed again along with a pH test. The pH tests of NaCl and NaC2H3O2 did not match that of the unknown white compound. The list of compounds had been entirely ruled out. The identity of the unknown white compound was revealed to be calcium chloride. To synthesize at least a gram (calculated to produce 1.2g) of CaCl2, the following reaction was completed.
Based the data collected, the identity of the unknown #42 is lithium chloride. Because the unknown compound produced a bright red pinkish flame, shown in Table 1, the possible cations based on the CRC Handbook were lithium or strontium 1.The known 1M lithium chloride also produced the same colored flame as the unknown, suggesting that the unknown compound has lithium. Since lithium produces no precipitate with the compounds in Table 2 and strontium produces a precipitate with the same compounds, the observations in Table 2 indicate that the unknown’s cation is lithium 4. Using the solubility table, process of elimination, and the results in Table 3 the possible anions for the unknown compound were chloride and bromide4. The production of precipitate
Eleven mystery test tubes labeled from K-1 to K-11 contained: 6M H2SO4, 6M NH3, 6M HCl, 6M NaOH, 1M NaCl, 1M Fe(NO3)3, 1M NiSO4, 1M AgNO3, 1M KSCN, 1M Ba(NO3)2, 1M Cu(NO3)2 respectively. The contents of the test tubes were determined by chemical experiments. Solution K-1 contained NiSO4 because when solution K-9, ammonia which was identified by its pungent odor, was added, an inky dark blue color was made. Iron (Fe (NO3)3) was determined to be in test tube K-2. KSCN was found in test tube K-11 since Fe (NO3)3 and KSCN makes a bloody color when mixed together. Flame tests were conducted in which K-8
The flame test had a variety of results. Most of the known compounds did not match our unknown except for Ca(NO3)2. Both Ca(NO3)2 and the unknown compound had a deep red/orange color flame. While Ca(NO3)2 had the closest results two other compounds had slightly different results but not different enough to rule them out. Those other two compounds were CaCl2 with a yellow/ orange color and CaCO3 with a reddish color.
As a result of this lab experiment, the hypothesis is attested to be precise as the ionic compounds did go through a double displacement reaction. The purpose of this experiment was to establish what occurs when two pairs of compounds react with one another. The information collected while doing the lab has allowed more knowledge to be obtained, as one can visibly see the changes happening and different signs of chemical changes. The cations and anions in the ionic compounds have successfully exchanged places with one another, creating the compounds with the different properties evident in the observation given. For example, precipitates were visible in almost all reactions in this experiment. Therefore, this lab experiment was held to demonstrate
Zainulabidin Adhami BB3 Experiment 3: The Gravimetric Determination of Calcium Abstract: The Gravimetric Determination of Calcium Lab utilized homogenous precipitation to determine the percent Calcium (Ca) in an impure sample of Calcium Carbonate (CaCO3). Three samples of 0.3574g, 0.3500g and 0.3736g of an impure sample of Calcium Carbonate (CaCO3) were added to three beakers, two of which were 250 ml and one which was 400 ml. These three samples were reacted with many different substances. After the reaction, presented above, was completed, the solution was promptly put into a vacuum filtration and then subsequently massed.
owing for a percentage yield of 74.###%. A percentage yield of 11#.##% was also calculated, had the
The cations in both the known and unknown samples were identified by using qualitative analysis, of which were determined to be acidic, basic, or neutral by using litmus paper. Acid-base reactions, oxidation-reduction reactions, and the formation of complex ions are often used in a systematic way for either separating ions or for determining the presence of specific ions. When white precipitate formed after adding hydroxide, aluminum ion was determined to be present in the solution. However, nickel was determined to test positive when the solution changed to a hot pink color after adding a few drops of dimethylglyoxime reagent and iron was present when the solution was a reddish brown color when sodium hydroxide was added to the mixture at the very beginning of the experiment. Qualitative analysis determines that ions will undergo specific chemical reactions with certain reagents to yield observable products to detect the presence of specific ions in an aqueous solution where precipitation reactions play a major role. The qualitative analysis of ions in a mixture must add reagents that exploit the more general properties of ions to separate major groups of ions, separate major groups into subgroups with reactions that will distinguish less general properties, and add reagents that will specifically confirm the presence of individual