Lesson written by Carolina Sylvestri Experiment: Reaction Between Ions in Aqueous Solutions The Monster Mash Background: Ionic solids dissolve in water to form aqueous solutions which conduct electricity. These solutions contain both positive and negative ions in such numbers that their net electric charge is zero. In this experiment, you will mix various ionic solutions, two at a time, to determine which combinations form precipitates. Knowing which ions are present makes it possible to deduce which of the possible ion combinations are responsible for the precipitates. From your data table, it will then be possible to generate a solubility table.
These tests consisted of a wafting test, a solubility test in deionized water, and a pH test. The unknown’s characteristics, discovered through the physical tests, were then compared with known cations: Sodium, Potassium, Calcium, Ammonia, and Magnesium. Flame tests were performed in order to classify the unknown cation. A small amount of the solid unknown ionic compound was placed on a watch glass. A wet swab was used to collect a small sample of the compound.
Juliana Park Mayumi Tamada CHEM 111B LAB/ M-F 1-4PM 15 August 2012 Spectroscopy Lab Introduction In this lab, the molar absorptivity of the complex FeLn2+ will be determined by using the absorbance of the complex and its concentration. The absorbance will be found by using a spectrophotometer. For the next part of the lab, the formula of the complex will be determined by also using the volume of ligand and the absorbance again. Experimental There are two different parts to the experiement. In the first part, five 100 mL flasks of 5 mL ligand solution, 5 mL 2 M sodium acetate, 4 mL 3 M NH2OH, and 1-5 mL Fe2+ solution are diluted with water.
Predicting an Unknown from Logic Trees Project 2 Report Ashley Garcia* Ayland Smith Introduction The purpose of the project was to use elimination and confirmation tests on several anions and cations to form a logic tree. Cations used in part 1 are potassium, iron (III), zinc (II), copper (II) and cobalt (II), and the anions in part 2 are chloride, carbonate, nitrate, and sulfate. The unknown contains both a cation and an anion. The logic trees from part 1 and part 2 were then used to identify an unknown. Materials and Methods Part 1 For the cation elimination test first 10 drops of potassium, iron (III), zinc (II), copper (II), and cobalt (II) were added to 5 centrifuge tubes and the color was recorded.
L a n d o l t C l o c k A B S T R A C T An experiment was designed to see if the Landolt iodine Clock is an elementary reaction or not. This was achieved by finding the four unknown variables (α, β, A, and Ea) for the reaction of 2I- + S2O32- → I2 + 2SO42-, which comes from the two reactions that drive the Landolt Clock: I2 + S2O32- → S4O62- + 2I- and I2 + starch → I2 • starch complex. α and β were found experimentally by changing the concentrations of KI(aq) and (NH4)S2O8(aq)—solution’s concentration was held constant while the other was doubled; both variables were found to be roughly equal to 1. Variables A and Ea were found by keeping the concentration of all solutions constant while changing the temperatures. Using a graph of ln(K) vs. 1/T, Ea was found to be .00426 KJ/mol and A was found to be 2.4033 s-1.
Materials & Methods Identifying the unknown compound solution (#2314) first required the identification of each individual solution. One drop of each solution was added to five individual wells of a spot plate. Next, three drops of 3M hydrochloric acid (to be referred to from now on as HCl). The spot plate was then cleaned, and the procedure above was recreated two more times, the second test done by adding 3M ammonium hydroxide (NH4OH), and the third by adding 1 drop of dimethylglyoxime (DMG). All color observations were recorded and compared to the known behaviors of the focus metals.
Reaction Order and Rate Laws Abstract The purpose of the experiment is to determine the rate law for a reaction between hydrochloric acid (HCl) and sodium thiosulfate (Na2S2O3) and once found to calculate the k or specific rate constant of the reaction. To determine the reaction order and rate constant; two experiments with several trials of each will be conducted. First, the concentration of HCl will be changed while the concentration of Na2S2O3 is held constant. Next, the concentration of Na2S2O3 will be varied while the concentration of HCl is held constant. From this experimental data it is found that HCl is zero order in the reaction and Na2S2O3 is first order.
Prelaboratory preparation: Read pages 1 – 30 and 45 – 54 of the lab text. You may disregard the microscale distillation procedures of TECH 0704. Answer in your laboratory notebook the Safety Quiz on pages 11 – 12 and the Prelab Questions 1, 2a, 2b, 3 -5, pp. 67 - 68. EXPERIMENT: TECH 0704, Distillation, macroscale technique only, simple and fractional: Substitute a mixture of 25 mL ethanol and 25 mL water for the toluene/cyclohexane mixture.
There are two parts to this lab. Part 1 which will be a known hydrate CoCl2 ∙6H2O or Cobalt (II) Chloride hexahydrate, and Part 2 which will be an unknown hydrate. Equations and Mechanisms * Moles of hydrate and water ratio: Moles of water Moles
What might you have used in the above experiment to get this color change to happen in the solution? At what pH would the solution have been neutral? 4. If you had walked into the lab, only to discover that you only had 0.1 M sulfuric acid available to run your tests, how might this have affected your calculations? Why?