Question

Which of the following compounds can be detected by Molisch’s test?

(a) Sugars 

(b) Amines

(c) Primary alcohols 

(d) Nitro compounds

Answer 1

(c) : The elements with high negative value of standard reduction potential are good reducing agents and can be easily oxidised. 

Thus X should have high negative value of standard potential than Y so that it will be oxidised to X²⁺ by reducing Y²⁺ to Y. 

X = Zn, Y = Ni 

Zn + Ni²⁺ → Zn²⁺ + Ni 

Alternatively, for a spontaneous reaction E° must be positive. 

E° = E°_{reduced species} – E°_{oxidised species} 

= – 0.23 – (– 0.76) 

⇒ E° = + 0.53V