Question

# Discuss the chemistry of Lassaigne’s test.

Hint: Lassaigne’s test is used in case of mainly in the detection of the first element of group 15 and 2nd and 3rd period of group 16 and group 17 elements, i.e. to test their presence in the hydrocarbons. It is done with the help of alkali metals. So, we can explain the test with the help of reactions.

Na + C + N $\rightarrow$ NaCN
2Na + S $\rightarrow$ Na$_2$S
Na + X $\rightarrow$ NaX (X = Cl, Br, or I)