pnb lab practice

Topics: Distillation, Water, Evaporation Pages: 2 (1099 words) Published: November 2, 2014

2. From the plots of the boiling point versus the volume of distillate in the simple distillation experiments, what can you conclude about the purity of your product? Product not very pure. No distinct line to know when one begins and one ends. Distillation of cyclohexane and toluene crossed over into the other's range. Would need to perform more distillations to better purify the solvents. 5. What is the effect on the boiling point of a solution (e.g. water) produced by a soluble non-volatile substance (e.g. sodium chloride)? What is the effect an insoluble substance such as sand or charcoal? A soluble, nonvolatile substance such as sodium chloride will raise the boiling point of an aqueous solution. An insoluble substance will have no effect on boiling point of a solution. What is the effect of each of the following on the observed boiling point? a) The presence of a non-volatile impurity?

A soluble, nonvolatile substance will raise the boiling point of an aqueous solution. Insoluble substance will have no effect on boiling point of a solution. b) If you place the thermometer bulb too high (is not kept moist with condensate? The vapor will not reach to the thermometer bulb, Boiling point lower than should be. 6. you have to understand that when something is a certain temperature not all of the molecules are the same temperature In any given substance with a "temperature" of 50 C, we might have some molecules at 0 C and some molecules at 100 C for a brief period of time. This explains why wet stuff at room temperature (25 C) can dry out: over time, some of the molecules reach a temperature sufficient to "break free" from the liquid, becoming a gas. This isn't limited to liquids either! Even ice in your fridge will lose molecules, leading to the puzzling "shrinking ice cube" effect and the ever popular "freezer burn" where $10 sirloin steaks are reduced to dried out slabs of meat. Now, I'll answer your question: why doesn't something IMMEDIATELY...
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