IDENTIFICATION OF UNKNOWN COMPOUNDS USING PHYSICAL PROPERTIES PRE-LABORATORY DAT
ID: 1081549 • Letter: I
Question
IDENTIFICATION OF UNKNOWN COMPOUNDS USING PHYSICAL PROPERTIES PRE-LABORATORY DATE NAME Directions. For the following questions used the table of physical properties of compounds on page 77 as your source for possible identities. 1. Is benzophenone a liquid or solid at room temperature? How do you know? Which solventis) would you expect benzophenone to dissolve in? y must you determine if your thermometer is reading acecurately before you determine the boiling point of your liquid unknown? What would you do if you determine that it is NOT reading accurately? 3. A student tested her liquid unknown and determined the density to be 0.85 g/mL, the boiling point to be 108°C, and that the liquid is insoluble in water, soluble in cyclohexane, and partially soluble in ethanol. What is the best conclusion about the identity of the liquid unknown? 4. After gathering the data for his solid unknown, a student cannot decide between two or the possibilities in the table of possible compounds. The unknown melted at 73°C, was insoluble in water, and soluble in cyelohexane. It was partially soluble in ethanol. The density of the solid was estimated to be > 1.00 g/mL due to the fact that the solid sunk in water. a. Which two substances from the list of possibilities could the unknown be? b. What is the BEST choice? Defend you answer.Explanation / Answer
1. Benzophenone is a solid at room temparature.
We can know this as it melts at 48C and boils at 306 C.
So,room temparature i.e. at 25C Benzophenone is solid.
2.Organic compund(non-polar) dissolves in organic and non-polar solvent .So, Benzophenone will dissolve in Cyclohexane and Ethanol.
3.it is necessary to check the accuracy of the thermometer otherwise we will not get the appropiate boiling temaparature and the experimental liquid will boil either at temparature lower than its actual boiling point or higher.i.e we will get incorrect boiling temparature.
4.The organic compund should be Stearic acid which can be said from density and solubility data.But, Boiling point has been measured incorrectly .