Unknown Solid Identification General Chemistry 101/102 Laboratory Manual University of North Carolina at Wilmington

Unknown Solid Identification Purpose To identify a solid substance based on its physical and chemical properties. Safety Considerations Exercise caution when handling the NaOH and HCl solutions. These are fairly concentrated solutions and may cause burns. Dispose of all liquid wastes in the waste jar in the hood. Place solid wastes in the solid waste container.

Unknown Solid Identification Procedure Prepare a saturated solution of your unknown. Use this solution whenever a test calls for using the unknown solution. saturated solution Test 1: Record the color of your unknown solid and solution. Test 2: Record the odor of your unknown solid and solution. http://www.nabt.org/sup/publications/ nlca/nlcapdf/11NLCAchp9.pdf Test 3: Add 10 drops of 1 M NaOH to 10 drops of your unknown solution. Gently warm the test tube to check for the odor of ammonia.

Unknown Solid Identification Procedure Test 4: Test the acid/base properties of your unknown solution with litmus paper. bases turn red litmus blue acids turn blue litmus red Test 5: Clean a wire test loop and conduct a flame test using your solid unknown. clean wire has only faint yellow flame use small amount of solid for flame test

Unknown Solid Identification Procedure Test 5 (cont.): Identify the cation present in the flame test. Na+ flame test Ca2+ flame test Li+ flame test K+ flame test

Unknown Solid Identification Procedure Test 6: Add 10 drops of 6M HCl to a small amount of the solid unknown to test for the presence of the carbonate ion. Test 7: Add 2 drops of 0.1 M AgNO3 to a small amount of the unknown solution in a spot plate to test for the presence of Cl -, Br -, I-, or CO32- ions. AgCl AgBr or AgI Ag2CO3

Unknown Solid Identification Procedure Test 8: Add 2 drops of 0.1 M Pb(NO3)2 to a small amount of the unknown solution in a spot plate to test for the presence of Cl -, Br -, I-, or CO32- ions. PbCl2 or PbBr2 PbI2 PbCO3