Inorganic Qualitative Analysis (QUAL) 17 Concept/Skills Development Common Student Misconceptions 1.    “Insoluble means nothing dissolves.” Solubility is a relative term defined quantitatively by a solubility product (an equilibrium constant). At the qualitative level, an insoluble substance is defined in many texts as a substance that can only form solutions of less than 0.01 M. 2.    “Separations are clean.” Notechniquecancompletelyandperfectlyseparatethecomponentsofamixture. 3.    “Analysis is easy.” Chemical  analysis  is  sometimes  expected  to  answer  such  questions  as: “What’s in this barbecue sauce?” It is thought that all that is necessary is to perform a simple test or analyze a sample with an instrument, and the answerrevealsitself.Actually,quitealotofintellectualeffortisoftennecessary. See “The Past 100 Years in Analytical Chemistry,” by G. Ewing in References. Twoanecdotes(Oesper,1975)arerelatedtoflametestsandthequalitativeidentification of metal ions. The first of these concerns Frederick Soddy (1887-1956). During a visit to Paris, he received a few milligrams of radium bromide from Marie Curie. When he returned to London and the laboratory of William Ramsay, for whom he worked, he watched in horror as Ramsay used up most of his sample to do an unnecessary flame test to confirm that the sample contained radium. The second anecdote concerns Robert Wood  (1868-1955),  who  studied  chemistry  under  Ira  Remsen  at  Johns  Hopkins University. Wood took his meals at a boarding house. It seems that whenever steak was served for supper, beef hash was served at the following breakfast. The patrons of the boarding house suspected that table scraps were used in preparing the hash. One eveningWoodleftseveralpiecesofsteakonhisplateafterhesprinkledonitwhatlooked like table salt, but was actually lithium chloride. The next morning he burned a piece of hash in the table lamp flame, saw the brilliant red color characteristic of lithium, and proved to the delight of his fellow diners that their suspicions were correct. 1.    Sing a song of Sulfide A beaker full of lime... Four and twenty test-tubes Breaking all the time. When the cork is taken out Fumes begin to reek... Isn’t that an awful mess To have five times a week? CHEM 13 NEWS, October 1969, p. 84 2.    TENCOMMANDMENTSFORSTUDENTSOFANALYTICALCHEMISTRY 1.    Thou shalt honor thy neighbor’s olfactory sensibilities. 2.    Thoushaltnotkillunlessthoucanstprovethathedidspitinthyunknowns. 3.    Thou shalt not pencil titrate. 4.    Thou shalt not take the name of thy teacher in vain. 5.    Thou shalt not remain forever on the pans of thy balance. 6.    Thou shalt keep thy desk spotless that thy days may be long in this laboratory. 7.    Thou shalt not commit adulteration—of reagents. 8.    Thou shalt love the lab assistant as thyself. 9.    Thou shalt not covet thy neighbor’s success, nor clean equipment, nor anything that is thy neighbor’s. 10.    Two days shalt thou labor, sweat and swear in thy laboratory; the other days are set aside for thy teacher’s peace of mind and for the conservation of thine own sanity. CHEM 13 NEWS, January 1978, p. 1292 HUMOR: ON THE FUN SIDE HISTORY: ON THE HUMAN SIDE