# An Introduction to Qualitative Analysis

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An Introduction to Qualitative Analysis Purpose: Tests the ions of Mg2+, Ca2+, Sr2+, and Ba2+, and identify them separately. By using these observations, identify the unknown ion. Then tests the ions of SO42-, CO32-, Cl-, and I-,identify them separately, and use the observation to identify the unknown. Procedure Part I - Qualitative Analysis of Group 2 Elements Mix 0.02M K2CrO4 with each Mg(NO3)2, Ca(NO3)2, Sr(NO3)2 and Ba(NO3)2 together. Secondly, mix 0.1M (NH4)2C2O4 instead of 0.02M K2CrO4 together with the same reactants used before. Thirdly, mix 0.1M Na2SO4 with those reactants. Then, mix 0.1M NaOH with the same reactants used before again. Some precipitates should forms ,record the observations in Table 1.…show more content…
State the identity of your unknown (along with its sample number). Give the reasoning you used to arrive at this conclusion. The Unknown Z should be SO42- because it has a same property as SO42- does. When SO42- is added to Ba(No3)2, and AgNo3, it forms a ppt; for the unknown anion, when it is added to Ba(No3)2, and AgNo3, it forms a ppt as well. When HNO3 is added to BaSO4, the ppt disappeared; for the unknown anion, when HNO3 is added to unknown, the ppt disappeared too, therefore we can conclude that the unknown is SO42-. Follow-Up Questions: 1. Devise a sequence of reactions to follow (using filtering or centrifuging where necessary to remove precipitates) to identify an unknown containing two or more cations of Group 2 elements. The Group 2 elements are Mg, Ca, Sr, and Ba. To identify an unknown containing two or more cations of Group 2 elements, first add CrO4 into the solution. Then we could identify them with their colour. Next we add C2O4, if the ppt is formed, then we know Ca2+ is involved in the solution. Next we add OH into the solution, if a ppt formed, that means Mg2+ is involved in the solution. 2.Devise a sequence of reaction to follow (using filtering or centrifuging