University Teknologi MARASabah BranchFaculty of Applied SciencesDiploma in SciencesCHM 260 LABORATORY REPORTExperiment Number: 03Title: Qualitative Analysis of Group III CationsLab Partners Name:1. Ramona binti Masri2. Siti Nurajjar binti Jami (2010673706)3. Suliana binti Salim4. Yusliana binti YusofLecturers Name: PM. Gan Gin HoonDate of Submission: 23rd JANUARY 2013

1.0 TITLE: 1.1 Qualitative analysis of Group III cations: Fe2+, Fe3+ Al3+, Cr3+, Co2+, Ni2+, Mn2+,Zn2+.

2.0 OBJECTIVE:2.1 To identify the group III cations in solutions.

3.0 INTRODUCTION:Qualitative analysis is useful in detecting the presence of specific ions in an aqueous solution. It is an analysis that falls under the general category of analytical chemistry, which will make it able to answer the question of; "What is in a sample?". The basis for a qualitative analysis is the fact that ions will undergo specific chemical reactions with certain reagents to yield observable products. For example, silver ion can be precipitated with hydrochloric acid to yield solid silver chloride. Because many cations will not react with hydrochloric acid in this way, this simple reaction can be used to separate ions that form insoluble chlorides from those that do not. In fact, the qualitative detection of ions in a mixture is commonly accomplished by a system of analysis in which precipitation reactions play a major role. In addition, acid-base reactions, oxidation-reduction reactions, and the formation of complex ions are often used in a systematic way for either separating ions or for determining the presence of specific ions. The qualitative analysis of ions in a mixture must follow a scheme that can be summarized as follows: (i) Add reagents that exploit the more general properties of ions to separate major groups of ions; (ii) Separate major groups into subgroups with reactions that will distinguish less general properties; and (iii) Add reagents that will specifically confirm the presence of individual ions. For a successful qualitative analysis, the order of reagent addition is crucial and should follow the order of; group I first, group II second, and so on. For example, addition of carbonate first would precipitate everything but the group V ions or addition of basic H2S first would precipitate all group II and group III ions.

4.0 CHEMICALS:4.1 Solutions of Fe2+, Fe3+ Al3+, Cr3+, Co2+, Ni2+, Mn2+ and Zn2+.4.2 NH34.3 NaOH4.4 K2CrO44.5 KSCN4.6 K4Fe(CN)64.7 PbO2 powder4.8 HNO3 (concentrated)4.9 Solution C

5.0 PROCEDURE

5.1 Part A: Reactions of Group III cations.

5.1.1 Apart from Fe3+, all other elements were dissolved to become solutions first before being tested.5.1.2 The first test was using the NH3 solution as the reagent. A small amount of NH3 solution was added into the sample, and then followed by an excess amount of the reagent.5.1.3 Next, a small amount of NaOH solution was added into the sample, followed by an excess amount of the reagent.5.1.4 For the third test, some potassium thiocyanate, KSCN solution was added into the sample.5.1.5 Some potassium hexacyanoferrate (III), K4Fe(CN)6 solution was added into the sample.5.1.6 The final test was to add small amount of potassium cyanide, K2CrO4 solution into the sample, and then followed by an excess amount of the reagent.5.1.7 But for Mn2+, there was a sixth test, which was some PbO2 powder was added first into the solution. Then, some concentrated HNO3 was added into the mixture. After that, the solution was heated to boil. The colour change was observed.5.1.8 All of the observations were recorded in a table.

5.2 Part B: Identification of the cations present in unknown samples.5.2.1 All tests in Part A were carried out on Solution C, including the sixth test. 5.2.2 The cation present in Solution C was identified.

7.0 DISCUSSION:

When NaOH added to Fe2+ solution which is already prepared in five test tube, the mixture turn from light green to dark green and there was form a precipitate. Whereas for KSCN solution, when we added it into test tube filled with Fe2+, the mixture turn from light green into light orange and when we added in excess, there is no changes. As we added NH3 solution, as based on our observation, we found the mixture was turn from light green into dirty green and as we added in excess there is no changes. Besides, when we added K2CRO4 solution, we found the mixture turn from light green to dark brown and when we added in excess, there was no change. When we added K4Fe(CN)6 solution into test tube filled with Fe2+ solution, we found the mixture in the test tube turn from light green to dark blue.When we added NaOH into test tube filled with Fe3+, we found the mixture was turn from orange into brown and the precipitate was formed. When we added in excess the mixture was not dissolve. When we added KSCN solution into test tube filled with Fe3+ solution, the mixture turn from orange to dark brown. For NH3,when we added it into test tube filled with Fe3+,the mixture turn from orange into brown and its was form a precipitate. When we added K2CRO4 into the test tube filled with Fe3+,the mixture turn from orange to dark orange. When we added K4Fe(CN)6 solution into test tube filled with Fe3+ solution we found the mixture turn the orange colour into dark blue.When Cr3+ which is green in colour was added with drop wise NH3 which white in colour, the solution turned to greenish. When NH3 added in excess, the solution then turned from greenish to greyish blue in colour. Next, the Cr3+ was added with drop wise NaOH which is also white in colour and the mixed solution turned to light green and when it is added in excess, the light green colour of the solution remain constant. After that, Cr3+ was added with KSCN which white in colour and it was observed that no reaction occurs. The green colour of the Cr3+ remains constant. Then, yellow in colour of K3Fe(CN)5 was added to Cr3+ and it was observed that no changes occur. Lastly, Cr3+ was added with drop wise K2CrO4 which is also yellow in colour resulting the solution colour changes from green to yellowish green in colour. Then, when it was added in excess, the solution turned from yellowish green to dark yellowish green in colour.When drop wise NH3 solution was added to Co2+, blue precipitate was formed. After that, when NH3 was added in excess, the precipitate do not dissolved. Next, blue precipitate also formed when drop wise of NaOH was added into Co2+. However, the blue solution turned colour from blue to pale pink when NaOH was added in excess and the precipitate do not dissolved. When dropwise of KSCN added to Co2+, no changes occur same when it was added in excess. Dirty green precipitate formed when K3Fe(CN)5 was added into Co2+ in dropwise while in excess, the precipitate formed do not dissolved. After that, when Co2+ added with K2CrO4, the solution turned to orange and no precipitate formed. While when excess K2CrO4 added, the orange solution change colour to brown.Dropwise NH3 added to Mn2+ resulting white precipitate formed and more precipitate formed and the precipitate do not dissolved when NH3 added in excess into Mn2+. After that, dropwise NaOH added into Mn2+ causing white precipitate to form and the precipitate do not dissolved when NaOH added in excess into Mn2+. Next, when KSCN was added into Mn2+, no changes occur and the solution remains colourless. Then, Mn2+ added with K3Fe(CN)5 and white precipitate formed. The solution of Mn2+ turned from colourless to yellow when added with dropwise K2CrO4 and when it was added in excess, the solution turned from yellow to dark yellow. Lastly, the Mn2+ added with PbO2 and black precipitate formed. Then the solution added with HNO3, resulting the precipitate to dissolved. After that, the solution heated and the black solution turned to dark purple in colour.When Zn2+ was mixed with a little of ammonia NH3, white crystal precipitate was formed and the precipitate was dissolved when an excess of ammonia mixed to the solution of Zn2+. When a little of sodium hydroxide , NaOH was added to the solution of Zn2+, white crystal precipitate is formed and it dissolved when an excess of it added to the Zn2+ solution. There is no reaction formed when KSCN was added to Zn2+ solution which is the colour of the solution remained constant. A white precipitate is formed when K4Fe(CN)6 was added into Zn2+. The colour of the Zn2+ solution change from colourless to light yellow and the colour of the solution is change from light yellow to bright yellow when an excess of K2CrO4 was added to the solution.A white precipitate is formed when a little of NH3 is added into the solution of Al3+ and not dissolved when an excess of it was mixed to the solution. When NaOH is added the solution of Al3+ , white precipitate is formed and it is dissolved when an excess of NaOH is mixed with the solution. There is no reaction when KSCN is added to the solution. When K4Fe(CN)6 is mixed to the solution of Al3+ , the colour of the solution change to greenish grey and light blue colour was formed when an excess of K4Fe(CN)6 is added to the solution. A milky light yellow of colour was formed when K2CrO4. The colour of the solution change from green to greenish blue when NH3 is added to the solution of Ni+ and blue precipitate is formed. When an excess of NH3 is added to the solution, the colour change from greenish blue to blue and the precipitate is dissolved. The colour of the solution is unchanged and pale green precipitate is formed when NaOH is added with Ni+ and the mixture showed no reaction when an excess of the NaOH is added to the Ni+ solution. When KSCN is added to the Ni+ solution, the colour of the solution remains unchanged and no reaction occur when an excess of KSCN is added to the solution. A pale green precipitate is formed and the precipitate is not dissolve when an excess of K4Fe(CN)6 is added into the solution. The colour of the solution changes from green to yellowish green when K2CrO4 is added into Ni+ solution. It showed no reaction when an excess of K2CrO4 is mixed to the solution.In part B, identification of the cation present in unknown samples. This is carried out by adding up NH3, NaOH, KSCN, K4Fe(CN)6, K2CrO4 into 4 test tube containing solution C. When we add 3 drops of NH3 solution into the solution C, we found the solution C formed white gelatinous precipitate and when we added in excess, there is no change. Whereas for NaOH, when we added 3 drops into it solution C we observe that the solution C form a gelatinous precipitate. When we added in excess there was no change. KSCN solution, when we added in 3 drop into solution C, we found there is no change on the mixture. When we added K4Fe(CN)6 solution into the solution C, we found the colourless solution turn to bright blue. When we added in excess, there is no change. K2CrO4 solution, when we added it in 3 drops into the solution C, we found the solution turn from colourless into yellow oranges. When added in excess the yellow gelatinous precipitate formed. HNO3 and PbO3 solution, when we added in 3 drops both of it into solution C, we found the black colour form after poured with both of HNO3 and PbO3 and after it is boiled, there was no changes occurred.

8.0 QUESTIONS:

8.1 Write the equation of the following reactions:8.1.1 Reaction between copper (II) ion and ammonia (limited and excess).

8.1.2 Reaction between iron (III) ion and KSCN.

8.1.3 Reaction between cobalt (II) ion and potassium cyanide (limited and excess)

8.1.4 Reaction that occurs when the mixture of Mn2+, PbO2 and HNO3 (concentrated) is heated.

9.0 CONCLUSION:9.1 Solution C has identified as Aluminium, Al3+ ion.