Name the two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any?
Sodium and potassium metals react violently with cold water. Three observations that we make are : (i) The metal floats on the surface of water. (ii) The reaction is exothermic. (iii) Hydrogen gas evolved catches fire. To identify the gas evolved, we pass the gas through soap solution. Soap bubbles are formed which rise up. When a burning candle is brought near the bubbles, hydrogen gas burns with a .pop. sound.
