Can somebody please in great detail explain this lab to me? What did I make? Ple
ID: 484569 • Letter: C
Question
Can somebody please in great detail explain this lab to me? What did I make? Please give me really good descriptions if you understand and don't copy from the internet :(
some intro:
l. Place a stir bar in a 125 mL Erlenmeyer flask. Add 15 mL of concentrated aqueous ammonia to the flask followed by 0.0467 mol of ammonium chloride. All the ammonium chloride to dissolve by gently stirring the mixture on a stir plate 2. Use a mortar and pestle to grind 6-7 g of CoCl2 6H2O. Weigh 0.0210 mol of the ground substance and carefully add it in small amounts to the ammonium chloride solution. Allow the mixture to stir for a few minutes 3. As the mixture stirs, carefully add 4 mL of 30% hydrogen peroxide drop wise to the warm slurry formed in step 2. Use a Pasteur pipet for the addition. 4. When the effervescence has ceased and the mixture cooled, slowly add 15 mL of concentrated hydrochloric acid (i.e. drop wise from a pipet). Continue allowing the mixture to stir As the mixture stirs, obtain two small beakers. Place 20 mL of distilled water into one beaker and 20 mL of 6 hydrochloric acid into the other beaker. Place both beakers into an ice bath for later use. 5. Heat the mixture from step (4) for 15 minutes in a boiling water bath (see figure below): Flask clamped in water bathExplanation / Answer
In this lab you have synthesized a coordination compound [Co(NH3)5Cl]Cl2 whose IUPAC name is Pentammine-chloro-Co(III) chloride.
Coordinations compounds are a special group of compounds formed between transition metals, either in +vely charged or neutral and non-metals or group of non-metals. Following ionization equilibrium desbribes how they are different from normal ionic or covalent compound.
When added in water : [Co(NH3)5Cl]Cl2 <==> [Co(NH3)5Cl]^2+ + 2Cl-
five NH3 molecules and one Cl molecule which I have written inside the bracket, will remain attached to Co. This is remarkable because had it been an ionic compound, it would have broken into individual ions in aqueous solution.
NH3 and Cl which are inside the bracket are known as ligand. metal ion + ligand = coordination compound. Another interesting feature of this cooordination compounds are that they are colored e.g the compound you synthesized in purple in color.
Synthesis of [Co(NH3)5Cl]Cl2 : Procedure
solution of NH4Cl ------> add CoCl2.6H2O -----> add H2O2 (to oxidise Co^2+ to Co^3+) ------> heat + HCl ------> [Co(NH3)5Cl]Cl2 forms ---------> separate, dry and weigh
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In the second part of this lab, you have synthesized a linkage isomers from [Co(NH3)5Cl]Cl2.
Linkage isomers are pair of compounds which have different connectivity to the metal. Lets consider a ligand -NO2. It can bind to the metal two ways: through N and through O. Difference in binding give results to two isomers which are called linkage isomers.
In the second lab you have synthesize [Co(NH3)5(NO2)l]Cl2 from [Co(NH3)5Cl]Cl2 by replacing the Cl (inside the bracket) with NO2. As described before two isomers will result :[Co(NH3)5(NO2)]Cl2 and [Co(NH3)5(ONO)]Cl2. First compound N is coordinated with Co and in the second O is ccordinated with Co.