AP EAMCET201921 Apr 2019Evening ShiftChemistryCoordination CompoundsActual
In the detection of nitrogen of an organic compound by Lassaigne's test, a prussian blue colour is obtained. This is due to the formation of which of the following complexes?
Options
- AFe 2 Fe ( CN ) 6
- BFe 4 Fe ( CN ) 6 3
- CFe 3 Fe ( CN ) 6 4
- DNa 4 Fe ( CN ) 6
Correct answer
B. Fe 4 Fe ( CN ) 6 3
Step-by-step solution
Detection of nitrogen is done with the help of Lassaigne's extract. It is boiled with iron sulphate and then acidified with concentrated with sulphuric acid. The appearance of a prussian blue colour confirms the presence of nitrogen. 1 .   Fe 2 +   +   6 CN - →   Fe CN 6 4 - 2 .   F 2 + → Fe 3 +   +   e -   In the presence of concentrated   H 2 SO 4 3 .   Fe CN 6 4 - + 4 Fe 3 +   →   Fe 4 Fe CN 6 3     &#