Question

Questions: Three bottles are found on a shelf with their labels missing. Three labels are found on the loor for 2-pentanol, 1-pentene, and heptane. What reaction(s) would vou run on the contents of these three bottles in order to tell which label belongs on which bottle? Please give not only the name of the test s) but the results ou would see which would allow ou to distinguish which bottle contained which compound.

Answer 1

Alkenes can be easily identified by using the Bromine test. This test requires the addition of brown coloured liquid bromine into the sample. Alkenes being unsaturated, bromine atoms attach themselves to carbon atoms at both ends of the double bond. As the reaction takes place, brownish colour of bromine rapidly disappears thus giving clear test of alkene presence. Both alkanes and alcohols will not react with bromine.

Now to differentiate between an alkane and alcohol, we can use solubility. Alkanes are highly insoluble in water whereas alcohols dissolve readily. Another test is addition of pure sodium or potassium metal to the sample. Alcohols react with these metals to produce hydrogen gas which is visible as an effervescence. Alkanes do not show any reaction.