Spot Analysis Lab

For the cation analysis, 0.566 g of an unknown compound was dissolved completely in 5mL of distilled water in a centrifuge tube, thus confirming this solution as a stock solution. A flame test was performed on the stock solution to give a general idea of what test was to e preformed on the stock solution deriving the information from our logic trees in part 1. The logic tree from part 1 and the flame test confirmed that we needed to conduct an ammonia test on the stock solution. To being the ammonia test, 15 M NH4OH was added drop wise (about 20 drops) to the stock and the color of the solution and the color of the solution was recorded. 10 more drops of 15 M NH4OH

Procedure: Preparation of solution of unknown hydrate: 1. A clean dried test was taken. 2. A sample of unknown hydrate was taken in test tube.

The objective is to determine the presence of a cation and anion by a chemical reaction through determining the presence of the cations and anions in an unknown salt.

In well 4A there was a chemical reaction between the sodium chloride and silver nitrate. There was a white precipitate formation which proves there was a chemical reaction.

To be able to complete this experiment various lab instruments were needed. This includes the use of beakers, test tubes, a metal spatula, wooden splints, and a Bunsen burner. The analysis begins with determining the physical traits of the compound. Then 0.15 grams of the unknown substance is mixed with 3 mL of distilled water to test

What cation(s) are present in the unknown sample? Explain your reasoning for both the presence and absence of each ion.

The metal ions for the two unknown salts were determined by comparing data. Additional Step: 11. Any used wooden splints were soaked and thrown away in the trash can. The flame test was mostly successful because some errors were made.

In this lab, a lab group will do multiple tests on water for contrasting ions. Tests confirming the absence or presence of the ion. The lab group will be dealing with five distinct solutions. A control sample, tap water sample, ocean water sample, and a distilled water sample. The group will also use a reference solution. A reference solution is a solution with a firm vigorous existence of the ion being tested. So, It is like an example of what the precipitate should look like when the ion is existent and visible in the water sample. The solution may or may not contain an ion. Compare the results with the performance of the reference sample. Finally, if an ion is present, a chemical reaction will happen, making either a precipitate or a solution

The salts were then poured into beakers and combined with 200mL of water to create solutions. A table was created to record the results of each combination of substances.

CH 204 – Introduction to Chemical Practice Experiment 1- Qualitative Analysis of Cations Anusia Mansukhani Andrea Martinez TA: Joseph Guerrera September 28th,2017 RESULTS & DISCUSSION The purpose of this lab was perform qualitative analysis an unknown solution and determine if the unknown cation. It was a combination of either lead and calcium, lead and barium, silver and calcium or silver barium. This experiment was divided into three parts.

Before being able to find the unknown ions inside the solution provided by the teacher, the ions needed to be examined for any physical or chemical changes to ensure the confirmation of each one. There were three separate sections to this lab, each one containing the same fifteen steps that needed to be followed to identify every ion. In the first part, the ions were given labeled in their original containers and divided into separate test tubes. Each ion was tested with the steps leading to their confirmation. Things such as color change or the formation of a precipitate signified a chemical reaction that confirmed the presence of an ion. This was used to give a better perspective on what would happen during the "real" lab procedure

To ensure maximum efficiency and meet time constraints, the steps in the procedure were performed quickly and but carefully. Most binary mixings produced clear colorless solutions, milky white solutions, or white precipitates. The mixings of the known solutions were recorded in Matrix 1; half of the fields were blocked out to prevent repetitions and same mixtures. The table produced many notable observations; for instance, water produced clear colorless solutions in all mixings and mixings with lead (II) nitrate usually formed precipitates. To identify the unknown solutions, qualitative analysis was performed on the unknown solutions and compared with observations of known solutions in Matrix 1. For example, Unknown Solutions 3 and 9 were easily identified as potassium iodide because of its

The problem arose when conducting the anion test to determine whether the unknown sample was additionally composed of either a sulfate or a chloride. Initially, our sample tested positive for both sulfate and chloride due the formations of white precipitates. These results indicated that the unknown sample would be potassium sulfate, but redoing the experimental test again led to the actual conclusion of a negative result for sulfate due to the absence of a white precipitate. With only a positive result for chloride, our unknown sample was in fact potassium chloride. Human error throughout the process of determining the weight of the precipitate with vacuum

Upon completion of each spot test, as well as initial pH tests, the results were then recorded. It was known that the 10 solutions consisted of 1 M hydrochloric acid, 1 M nitric acid, 3 M acetic acid, 1 M sodium hydroxide, 0.1 M silver nitrate, 0.1 M sodium chloride, 0.1 M zinc chloride, 0.1 M aluminum nitrate, 3 M ammonium hydroxide and 0.1 M lead nitrate, however their corresponding number was unknown. The first identified unknown was 98, acetic acid, given its highly prevalent scent, in addition to it not forming a precipitate with any substance due to the solubility rules. Given that two bases were present on the initial pH test, one being strong (93) and one being weak (91), it was then concluded that they were the strong base NaOH and the weak base NH4OH, respectively. Once identified, the precipitates formed by these two bases were then taken into account. Given that both bases reacted with the weak acid, 99, yet it drastically different manners (white and copper), it was then researched to see what would react with these bases to form a copper colored precipitate, resulting in AgNO3. Given that this was only one reaction, 99 as AgNO3 was not a fully supported result yet; further reactions would have to be considered. Next, the chemical reactions were written out to determine

Once the lab was completed, it was realized that there are different levels of reactivity between all metals. It was also realized that they react to different things such as Calcium reacting to water and the other four metals not reacting to water. To carry out the experiment, there was a set of steps that were followed to get results. All five metals were placed in water in separate test tubes to start with. Calcium was the only one that reacted with water while the rest of the metals didn’t. Those metals that had no reaction with water were taken aside and the water inside their test tube was poured out. Once the water was poured out with the metal remaining in the test tube, weak acid was poured in. The results of the four metals with acid were then observed and recorded.