A house wife while working in the kitchen get a cut on the finger. It started bleeding and become panic. She immediately called her neighbour. She had kept ferric chloride in her house. She immediately applied it on the affected area and the bleeding stopped.
(i) What is the chemical formula of ferric chloride ?
(ii) Why did bleeding stop on applying it on the affected finger?
(iii) What is the name of the phenomenon involved ?
  (iv) What is the value associated with this from the point of view of chemist? 

Explanation

(i) Chemical formula of ferric chloride is `FeCl_3`
(ii)` Fe^(3+)` ions of `FeCl_3` neutralize the charge on the colloidal particles of blood. This leads to coagulation of blood. Bleeding therefore, stopped.
(iii) This phenomenon is known as coagulation or flocculation
(iv) All house wives must keep small bag or kit in their kitchen. It must have ferric chloride kept in small bottle or potash alum, burnol and bandages etc. Minor accidents are very common in kitchen. The kit can be very helpful to deal with emergency.