Question

Which of the following is/are true statement(s)?
A) Caustic potash is a stronger alkali than caustic soda
B) Caustic potash is more soluble in alcohol than caustic soda
C) Caustic potash is used in organic reactions instead of caustic soda.
D) All of the above

Answer 1

Hint: Caustic soda is a pure crystalline and a colourless solid. It has a high tendency to get soluble in water but does not have the ability to be soluble in non polar solvents. The other name for caustic soda is lye. It is an ionic compound which white in colour.

Complete step-by-step answer:
Caustic soda is known as sodium hydroxide also. It has a bitter taste and when contacted with skin it has a slippery nature. It has the ability to absorb moisture so that it can form a series of hydrates. The chemical formula of caustic potash is KOH and for caustic soda is NaOH. In metal hydroxides the two bonds are present one is the metal oxygen bond and other is hydrogen oxygen bond.

The metal oxygen bond is a polar bond because of the presence of low ionization enthalpy of the metals. As the metal oxygen bond is polar so it will give its hydroxide ion readily. And we know that the molecule which gives its hydroxide ion easily is more soluble and has a stronger base than the one which does not give the hydroxide ion easily.

In potassium the size of K is small so its ionization enthalpy is less and due which the interaction of the nuclei with the outermost electron is less, so it will give its electron and the hydroxide ion easily and will be the strong base and will be more soluble in alcohol. Whereas in sodium the Na atom is bigger in size compared to potassium so it will have high ionization energy and will not give its hydroxide ion easily so it will be a weak base and would be easily soluble in alcohol. And as we know lattice energy is inversely proportional to size of cation. And in this case the cation is sodium and potassium.

The size of potassium is small so it will have high lattice energy. In the group as the size of the element increases the decrease in lattice energy is more than the decrease in hydration energy. And due to this reason the solubility increases with the increase in the molar mass. So the caustic potash will have more solubility than caustic soda. Caustic potash is used in organic reactions because it readily reacts with water and absorbs carbon dioxide in the moist state.

As it readily gives its hydroxide ion which is the nucleophile in the reaction so it is used widely in organic chemistry. The nucleophile of caustic potash attacks the polar bonds in the organic materials.

Hence the correct answer is option ‘D’.

Note: Caustic potash is used in the determination of the species of fungi and in the thickening of food. It helps in the fabrication of chips for semiconductors and in mercerizing cotton. It is used during the saponification of ester and in the production of bicarbonates.