Question

Give the formula of potassium carbonate.

Answer 1

Hint: We know that potassium is of first group it means it has only one electron in its outermost shell and it will form bonds by giving that one electron as alkali metals are good reducing agents. Try to make formulas using this knowledge, also note that carbonate is anionic part having charge $ - 2$ so while making formula these charges get cancelled.

Complete step-by-step answer:
If we recall the elements that are present in group $1$ these are Lithium, sodium, potassium, rubidium, cesium and francium. These elements have only one electron in their outermost shell which they will give to make a cation. Potassium is larger in size from sodium hence it will more easily give up the electron from its outermost shell to carbonate which is also having a $ - 2$ charge. These charges get cancelled and we will get a formula as- ${K_2}C{O_3}$

Commercially, potassium carbonate is prepared from potassium hydroxide $KOH$. It will react with carbon dioxide gas and make potassium carbonate also water. We can write the reaction between potassium hydroxide and carbon dioxide as follow- $2KOH\, + \,C{O_2}\, \to \,{K_2}C{O_3}\, + {H_2}O$
It is a solid of white color which is always present in hydrate form, you will see whenever you put it open it will absorb moisture from the surroundings. That’s why it's weighing process is difficult. We cannot weigh it directly.

Note: Not only potassium but all the members of the alkali group means all the elements of the group makes the same formula on reacting with carbonate ions. The preparation of the carbonate is different, while they are prepared commercially from different compounds of their own like here potassium carbonate gets prepared from potassium hydroxide which is having formula $KOH$ .