Discovering the Mystery of Eleven Test Tubes
Karen Radakovich Ph.D.
CH 223, Spring 08
Eleven mystery test tubes labeled from K-1 to K-11 contained: 6M H2SO4, 6M NH3, 6M HCl, 6M NaOH, 1M NaCl, 1M Fe(NO3)3, 1M NiSO4, 1M AgNO3, 1M KSCN, 1M Ba(NO3)2, 1M Cu(NO3)2 respectively. The contents of the test tubes were determined by chemical experiments. Solution K-1 contained NiSO4 because when solution K-9, ammonia which was identified by its pungent odor, was added, an inky dark blue color was made. Iron (Fe (NO3)3) was determined to be in test tube K-2. KSCN was found in test tube K-11 since Fe (NO3)3 and KSCN makes a bloody color when mixed together. Flame tests were conducted in which K-8 burned green which identifies Cu(NO3)2, and the solution from test K-10 burned yellow orange which indicates NaCl. Solution from test tube K-5 turned red litmus paper to blue which indicates a strong base (NaOH). Solutions in test tubes K-4 and K-6 are both strong acids which turned blue litmus paper to blue. Silver nitrate (K-7) produces precipitate with both acids and Barium nitrate can only produce precipitate with H2SO4 and it remains clear in HCl, K-3 precipitated with K-4 but did nothing with K-6, which proves that K-4 is H2SO4 and K-6 is HCl. Introduction:
1Water has many unique chemical and physical properties. Water goes through various reactions and possesses unusual properties to sustain life on Earth. Water has the ability to dissolve a wide variety of substances. Therefore, in nature, water has a variety of dissolved substances such as different elements, salts, gases. Any solution in which water is solvent is called aqueous solutions. Most aqueous solutions share the same chemical and physical characteristics, which makes it very difficult to identify without conducting various chemical tests. For determining the identity of unknown chemical solutions, it is important to understand the solubility and insolubility rules such as: precipitation, change in color, pH testing, litmus paper test, and flame test.
2There are different solubility and insolubility rules for all ionic compounds. All cations in group A1 (Li+, Na+, K+, etc), ammonium cation (NH4+), acetates (CH3COO-), most perchlorates (ClO4-) , and all common nitrates (NO3-) are soluble. All common iodides (I-), bromides (Br-), chlorides (Cl-), fluorides (F-) are soluble, except Hg22+, Cu+, Pb2+, Ag+ and those of Group 2A (2). All the sulfates (SO42-) except Ca2+, Sr2+, Ba2+, Ag+, and Pb2+ are soluble. Except those of Group 1A (1), ammonium (NH4+), and the larger members of Group 2A (2), all the common metal hydroxides, common carbonates (CO32-), common phosphates (PO43-) and all common sulfides (SO42-) are insoluble .
In a precipitation reaction, a precipitate forms which is an insoluble product formed from the two soluble ionic compounds reaction. Precipitation reactions are very common in nature and industries. Most of the deep-sea structures like hydrothermal vents are formed as result of this kind of chemical process. Most industries use precipitation reaction to produce inorganic compounds.
Litmus paper is used to identify if a substance is acidic or basic. There are different types of litmus paper. Red litmus paper which turns blue in the presence of a base and blue litmus paper which turns pink in the presence of an acid were used in this experiment. In this experiment eleven test tubes containing unknown solutions were provided. Which test tube containe H2SO4, NH3, HCl, NaOH, NaCl, Fe(NO3)3, NiSO4, AgNO3, KSCN, Ba(NO3)2, and Cu(NO3)2 were indentified. Some information was given about the reactions of all these aqueous solutions in the eleven test tubes as following: 1. H2SO4, sulfuric acid reacts with metals and produces insoluble sulfates; it is strong acid and counted as the most...
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