Point of Liquid Unknown D Boiling Estimated true (normab b.p. (apply corection t
ID: 714493 • Letter: P
Question
Point of Liquid Unknown D Boiling Estimated true (normab b.p. (apply corection to obtain) E. Unknown Identification Solild unknown inc Chlonde Liquid unknown QUESTIONS l. Is p-dibromobenzene a sold or a liquid at room temperature? alid 2. What solvent would you use to measure the density of napthalene acid? 3. Convert your densities to kg/L and compare these values with those in g/ml 4. If air bubbles were trapped in your solid beneath the liquid level in your density determinations, what error would result in the volume measurement, and what would be the effect of this error on the calcu- lated density? 5. A liquid unknown was found to be insoluble in water and soluble in cyclohexane and alkohol; the un- known was found to have a boiling point of 58 C at 670 mm Hg, Whatis the substance What could you do to confirm your answer? 74Explanation / Answer
(2)
In order to make density measurements, the solid should be insoluble in the solvent. We know that napthalene acid is not soluble in water. So the solvent that should be used to measure its density is water.
(3)
Since 1 kg = 1000 g, and also 1 L = 1000 mL, so we have:
1 kg/L = (1000/1000) g/mL = 1 g/mL
So the value of density will remain the same in both the units.
(4)
If air bubbles get trapped, then they would displace some extra water, and so the total volume of water displaced would be greater than actual. So the reported value of the volume of solid would be higher than its actual volume.
Since density = Mass//Volume, so because of higher volume, the density will be reported erraneoulsy as smaller than the actual value.
(5)
Here we use a nomograph calculator to find out the boiling point at 760 mm Hg, using the data given. We see that the normal boiling point for this compound is 610C.
Hence the compound is most probably chloroform, because it has very close boiling point value to this.
Also, it is non-polar which means it will not dissolve in water but in non-polar solvents like alcohols and benzene.