Question

What happens when calcium and potassium are put in water?

Answer 1

Hint: When a metal reacts with water at normal temperature then generally, hydrogen gas is liberated , along with a precipitate which is usually the hydroxide of the metal.

Complete answer:
In order to answer our question, we need to learn about the properties of calcium and potassium. Calcium is the element which has the atomic number of 20. Its atomic mass is 40u and is known to exist as an alkaline earth metal. Being so, it is a very reactive metal and that is why it is found in the combined state, in the form of compounds. It has the electronic configuration of $[Ar]4{{s}^{2}}$.
Potassium just comes before sodium, in the periodic table and possesses the atomic number of 19. Potassium is more reactive than calcium and if exposed to oxygen, it reacts to form peroxide. Potassium has an atomic mass of 39u and possesses the electronic configuration of $[Ar]4{{s}^{1}}$. It is a soft metal and has a silvery white appearance.
Now let us come to the question. Both calcium and potassium are very reactive and they react vigorously towards water. When calcium react with water, calcium hydroxide is formed, along with hydrogen and the reaction is represented below:
\[Ca+2{{H}_{2}}O\to Ca{{(OH)}_{2}}+{{H}_{2}}\]
Potassium also has a similar case. It reacts with the water to form the potassium hydroxide precipitate and also liberates the hydrogen gas. A lot of heat is produced in this reaction and there is formation of fire too. The reaction is represented below:
\[2K+2{{H}_{2}}O\to 2KOH+{{H}_{2}}+\Delta \]
These are the products formed when calcium and potassium react with water.

Note:
Potassium is a silvery soft metal that can be even cut with a knife. It is however stored in kerosene bottles which prevent it from reacting in the atmosphere.