Chemistry Lab Report

How do you know that it was not the non-metal ion whose colour you observed? (Hint:look closely at the names of the solutions that you tested). the non- metal ion which was chloride never changed and stayed the same for all the solutions, but the metal ions were all different for each solution. 3a. You were assigned two household items to test - what were common (non scientific) names of these items?

The unknown contained silver, as both the unknown and silver solutions turned red and formed red precipitates with the addition of potassium chromate.

It began as solid magnesium and now is ashy and crumbled. Upon adding water to the ashy substance, the substance turned gray. When only a little water was added, it appeared to push away the dusty sample. More water was added. Litmus paper was dipped into the substance.

To find the unknown #8 Alkaline I realized that the only anion that had 4 distinct precipitate reactions for each alkaline was H2SO4, so all I had to do was react Unknown #8 with H2SO4. I did this experiment and the reactant was milky white. Based on this reaction in comparison to my previous reactions I concluded that unknown #8 alkaline was the alkaline earth Ba. This experiment was most efficient because it only took one step to figure out what my unknown was, since their was four different reaction outcomes and four different earth metal each matching to one out come this was clearly the most efficient way.

Also a tray was provided that would be used to mix the ions and reagents. One by one the reagents and ions were mixed. Everyone had to make sure to write down what they observed. Some things that were noticed was color change,smell,texture, precipitation, and so on. Lastly the unknown ion must be identified by comparing it to the other ions.

The two experiments were, for the first experiment the group did the Magnesium and Hydrochloric acid (Mg and HCl)

The first experiment to be conducted was the synthesis/combination reaction, a piece of copper wire and magnesium ribbon is to be heated above the Bunsen burner. Make sure the Bunsen burner is on its medium setting before placing the copper wire above the flame. The copper wire will be held by a crucible tong over the flame of the Bunsen burner; it will take a few minutes in order for the new appearance of the copper wire to become visible. The copper wire was a reddish brown and solid before being heated. After it has been heated, it became slightly bent with a blackish gray color.

The objective of this experiment is to experimentally investigate which elements show similar chemical properties.

The essential way to assign an element to its unknown lab is by density, physical state and color. For example the unknown #1 was identified as silicon it’s physical state was solid, the density is 2.33 with a gray pigmentation therefore silicon belongs to the carbon family Group 14, because silicon and elements of the carbon family have similar behaviors. Another unidentified element was #4, it’s physical state is gas, with a density of 0.00374 and is colorless was distinguished as krypton which belongs in group 18 as a noble gas. Krypton is known as a noble gas because scientists have found traces of the gas in the atmosphere.

Virtual Lab: Developing a Metal Activity Series Purpose: To develop a metal activity series based on a series of potential metal and aqueous solution reactions. Procedure: The virtual lab was accessed by clicking on the following link. The student was directed to another page where they performed some virtual reactions between metal strips and aqueous salts and acids.

The fundamental purpose of this 3 part experiment is to determine cations via various tests, such as identifying cations with forming precipitates (qualitative analysis tests) or identifying cations with performing cation flame tests. Part A was mixing various chemicals to form specific types of precipitates that indicated the presence of a Lead cation or a Silver cation. Part B was similar to Part A, but Part B contained a false positive of whether the cation was Barium or Calcium (both had white precipitates). In Part C, various flame tests were performed, and the cation was determined by the color of the flame. In addition to determining cations, this experiment’s purpose taught how to use various equipment, specifically the centrifuge, the heat plate, and the bunsen burner.

The results obtained were consistent with the lab manual and the unknown sample aligned well with the instructions that were given. The unknown sample was labeled “3” which was then combined with HCl and centrifuged, decanted, combined with more HCl, centrifuged, and decanted again. The precipitate formed from the two latter steps was then boiled and then combined with acetic acid and Potassium Chromate to check for the presence of Pb2+. Upon mixing the precipitate with acetic acid and Potassium Chromate, a bright yellow solution was formed with no apparent precipitate. This bright yellow solution indicated that our unknown for part A contained Lead Chromate.

In conclusion, the chemical formula of the dehydrated sample was found to be CuCl2 and the formula for the hydrated sample was CuCl2 ·2H2O. Thorough experimental procedure was taken to obtain the water loss of the hydrated sample, therefore defining its chemical formula. As the hydrated sample of copper chloride changed colors throughout the heating process, a change in chemical composition was noted. The hydrate was originally a blue/green color, but as it was heated and lost its water, the hydrate turned brown. This chemical composition is known as the anhydrous residue.

From the unknown sample identified as #3, Parts A and B confirmed the presence of silver and calcium through precipitation reactions. From Part C, cation flame tests revealed the color characteristics of different metal cations: lithium produced magenta/pink, calcium produced scarlet, sodium produced orange, barium produced

Part III began with adding HCl to the unknown mixture. By using table 1.1 it is clear that the only ions that reacted with HCl were Lead and Silver. A precipitate formed so it became clear that either Silver or Lead was contained in the unknown solution. After being heated and centrifuged the remaining solid indicated a presence of Silver. The spot test tested negative for Lead.