CH 204 – Introduction to Chemical Practice Experiment #1 – (Qualitative Analysis of Cations) Valerie Tran* Kendrex White TA: Peiyu Tu June 08, 2016 RESULTS & DISCUSSION The purpose of this experiment was to identify the unknown cations in solutions in three different parts (A, B, C) using two types of qualitative analysis schemes. The first type of qualitative analysis scheme was utilized in Parts A & B. The qualitative scheme in Part A was primarily concerned with identifying lead or silver by analyzing the unknown metal nitrate solution. Part B’s focus was identifying barium or calcium in the unknown metal nitrate solution. The qualitative analysis scheme Part C utilized a different qualitative analysis scheme, the cation ion flame …show more content…
Through this experiment, the identities of the cations will be acquired and the types of qualitative schemes and proper use of lab equipment will become more familiar. The skill construction of a formula unit, total ionic, net ionic equations were acquired through the experiment. The results from Parts A & B were reasonable and expected. For Part A, the 6M HCl was added to the unknown metal nitrate (unknown number: 1) in Step 3 and immediately yielded solid white precipitate. The majority of the precipitate was at the bottom of the test tube, but there were bits of the precipitate in suspension. It looked similar to snow and was flaky. It was necessary to add HCl to the unknown because the cations must be completely precipitated in order for identification to be possible in this experiment. Cl- is soluble until it is combined to either lead, silver, or mercury. The addition of HCl can either yield lead chloride (PbCl2) which is slightly soluble or silver chloride (AgCl) which is insoluble . HCl also neutralizes any ions that contributed to the basicity of the solution, and in this case it was NO3- . In addition to neutralizing ions, HCl also affects Ba2+ or Ca2+to …show more content…
After (NH4)2CO3 was added to the basic solution, heat is applied to the test tube. It was then centrifuged and the liquid was discarded into a waste beaker. The precipitate was then washed with deionized water and centrifuged once again. Acetic acid was then added to the solid precipitate to dissolve it, resulting in a clear solution. Potassium chromate (K2CrO4) was added in step 12 because the chromate (CrO42-) ion and the unknown cation. This is vital in confirming the identity of the unknown cation in the metal nitrate solutions. Upon this addition of K2CrO4, the precipitate can turn yellow which presents the possibility of barium’s (Ba2+) presence. However, yellow precipitate was not a reliable confirmation of barium in solution. Assuming that barium ion was present could’ve led to a false positive. A false positive is when the test in an experiment resulted in an false, but seemingly correct
An error that could have been present during the lab includes not letting the zinc react completely with the chloride ions by removing the penny too early from the solution. For instance, the percent error of this lab was 45.6%, which was determined by the subtraction of the theoretical percent of Cu 2.5% and the experimental percent of Cu 3.64% and dividing by the theoretical percent of Cu 2.5%. This experiment showed how reactants react with one another in a solution to drive a chemical reaction and the products that result from the
Chemical Reactions and Identifications of Unknowns Data Analysis Name: _Gloria Smith_________________________________________ Please answer the following questions with complete sentences unless a fill in the blank is given. Your answers must be typed. Do not plagiarize! Identification Tests: Flame tests are used to identify the __metal ions_ of a compound. Litmus paper is used to identify acids and bases.
For this titration, one drop of EBT indicator, NH4Cl buffer, and the water sample were added to each well in a 1x12 well strip. Once each well was filled, the titration proceeded: one drop of the 2 x 10-4 M EDTA was added to the first well, two drops to the second, three drops to the third, etc. Once one of the wells turned a blue color, that particular well represented the point at which there was excess EDTA and all of the Mg2+ combined with the EDTA to remove the ions from solution and form the chelate. Following the test, the equation MEDTAVEDTA= MCa2+VCa2+ was used to calculate the Ca2+ and Mg2+ concentrations.1 Similar to the previous AA test, the water sample was diluted with a 1:1 ratio along with the Atherton and Virginia samples.
All Group two compounds were all white and crystal looking this was due to the reason that all these were salts and mainly all slats are white crystal looking. The pH levels of the compounds diverse from approx. 7 to some of the alkaline solution producing a pH of 10. The difference in the pH levels is due to the alkalinity or acidity of the corresponding bases. Sulphates, Chlorides all had relatively low pH’s suggesting that all these bases are weak bases.
The heating of the solution caused the reaction to start which decomposed Cu(OH)2 and made the solution colorless and darkened the precipitate. The fourth step was the formation of CuSO4. After the solution was decanted from the precipitate and washed with near boiling water, 6 M H2SO4 was added to the beaker containing Copper (II) Oxide and this caused the precipitate to dissolve and the liquid become clear blue. The last step was the formation of Cu(s). This step recovered Solid elemental copper.
Me and my lab partner Ariana camper had unknown solution C. we had 8 ions but we only used five out of the 8 and the five we used to be pb2+,Fe3+,Ca2+,NH4+ and Na+. we figured out that our solution had Lead, because during the experiment we separated the supernate and the precipitate; we retrieved the supernate and added 1M K2CrO4. As swiftly as possible we added K2CrO4 to the supernate. soon as I did that it turned yellowish rapidly. although, we had tested Ag+ we had no precipitate form in our solution.
Abstract In this experiment the separation of a copper (II) chloride and sodium chloride mixiture was attempted. The main aim was to separate the compounds from eachother while receiving as much of the original mass of both substances as possible - in perfect conditions the original mass will be received after seperation. Many techniques were considered but dissolution, filtration and evaporation proved to be easiest and most reliable in a school environment with school equipment. The copper (II) chloride and sodium chloride mixture was dissolved in a methanol solution and filtered out leaving the sodium chloride behind.
Afterwards, 0.1ml of ferroin solution (as an indicator) was added. Next, titration was performed. The contents in the conical flask was titrated with 0.1M ammonia cerium (IV) sulphate until a yellow solution was produced. The experiment was then repeated without sample B (only the H2SO4 and water in the proportion 3:7, 6ml acid 14ml
Elemental copper with its elemental charge of 0 will transform to (Cu+2) when reacted with nitric acid, which is an oxidation-reduction (redox) reaction. In reaction two, once the copper has dissolved, 20 mL of 6.0 M NaOH was added to the beaker, while the solution is being stirred. The precipitation reaction is observed since (Cu+2) transform into solid copper (II) hydroxide Cu(OH)2 with sodium hydroxide (NaOH). In the third reaction, the beaker was heated on a hot plate until the solution begins to boil because at this point, the blue Cu(OH)2 has been converted to black CuO. When heated, Cu(OH)2 will decompose into copper (II) oxide and water, which is a decomposition reaction. In reaction four, 5 mL of 6.0 M H2SO4 (sulfuric acid) was added to the mixture and within minutes of stirring, all the black CuO dissolved.
Chemical compounds that are available to determine are CaCO3, CaCl2, Ca(NO3)2, mgCl2, MgSO4, KCl, HCl, HC2H3O2, KNO3, K2SO4, NaC2H3O2, Na2CO3, NaCl, Na2SO4, HNO3, H2SO4, HNO3, H2SO4, NH4Cl, (NH4)2SO4, K2CO3, 0.1 M AgNO3, 0.2 M BaCl, Mg(s), NaOH, and KOH. To start this experiment, start with the flame test by gathering a Bunsen burner and a Nichrome wire. Connect the Bunsen burner with a rubber tube to a laboratory gas. To prepare solutions for the flame test, weigh out 0.205 gram of Unknown Compound using an analytical balance and mixed it into a 140 mL beaker filled with 20 mL ionized water. Ensure that solid is completely dissolved using a stirring rod.
For steps #2, 3 and 4, identify the type of chemical property that was observed. For steps #2, 3 and 4, the chemical property which was observed through the experiment is reactivity with a mixture. It was a mixture being featured because while copper sulphate is a pure substance, when it was added to the water, the copper sulphate became a mixture. I can justify which the property observed was reactivity with a mixture because all the steps consisted of reacting materials residing from different states of matter into the solution. The various reactions ranged from higher temperatures, to gas bubbles, to even colour
Introduction: The purpose of this experiment is to demonstrate the different types of chemical reactions, those including Copper. There are different types of chemical reactions. A double displacement reaction is a chemical process involving the exchange of bonds between two reacting chemical species. A a decomposition reaction is the separation of a chemical compound into elements or simpler compounds and the single-displacement reaction is a type of
After performing the lab, it is evident that one of the indicators of a double displacement reaction is the formation of a precipitate in an aqueous solution. This was seen through two of the reactions performed in this lab; sodium sulphate with barium chloride and lead (II) nitrate with potassium iodide. In the reaction between lead (II) nitrate and potassium iodide, both of the solutions were transparent liquids before they were mixed. However, after the solutions were mixed, a dark yellow precipitate formed within the aqueous solution. This indicated a chemical reaction occurred in this double displacement reaction.
This lab also tested basic chemistry techniques and calculations. The experiment consisted of making standard solutions that contained manganese (Mn) and 5% concentrated nitric acid (HNO3) that were measured for absorption to find their concentrations. Two unknowns were also measured and later their concentrations were calculated as well. The metal element of interest, in this case Mn, is measured in atomic absorption as how much light at a specific wavelength is absorbed when it goes through the atoms in the sample.
One of the possible systematic error that may occur in this experiment is that the hydrated (II) ammonium sulfate is contaminated as the iron (II) salt was left uncovered. The iron (II) salt was prepared by the lab assistant and the salt was left at the table uncovered for students to scoop the desired amount of salt they want. The iron (II) salt might be contaminated by dust particles and even saliva. This would cause the standard iron (II) solution to have less iron (II) salt in it and this means that less potassium permanganate solution is needed to titrate the iron (II) solution. This is a systematic error because the iron (II) solution used throughout the experiment.