Question

: Na reacts with water potassium cracks water.

Answer 1

Hint : We can easily explain the question if we know the reaction of sodium and potassium with water. With the help of reaction, we can easily demonstrate the reactivity of sodium and potassium with water and we can also describe the type of reaction.

Complete Step By Step Answer:
We will consider the reaction of sodium and potassium with water one by one. So, first, we will consider the reaction of sodium with water. The reaction is given below.
$2Na(s) + 2{H_2}O\xrightarrow{{}}2NaOH(aq) + {H_2}(g)$
From the above reaction, we can conclude that the elementary sodium reacts with water, gives sodium hydroxide as the product, and releases hydrogen gas.
When sodium is added to water, it melts and forms a spherical shape, and moves around the surface.
Now we will consider the reaction of potassium with water. The reaction of potassium with water can be given.
$2K(s) + 2{H_2}O(l)\xrightarrow{{}}2KOH(aq) + {H_2}(g)$
From the above reaction, we can conclude that potassium in reaction with water gives potassium hydroxide and hydrogen gas.
Now we will understand the reaction. When potassium is added to water, it melts and floats. It also moves around the surface of the water molecule. At the end of the reaction, sometimes there is an explosion that takes place which cracks water.
So here we can conclude that sodium reacts gently with water while potassium reacts violently with water as the molten metal spreads over the surface of the water molecule and exposes the large surface of the water.

Note :
Exothermic reactions are the reactions in which there is a release or evolution of energy. The reactions of sodium and potassium with water are exothermic. As we know that both the reactions result in the evolution of hydrogen gas.