Question

Select the correct choice:

• A. $KHC{O}_3$ is less soluble in water than $NaHC{O}_3$.
• B. $Ca{C}_2{O}_4$ is soluble in water and alkalies.
• C. $Ca(HC{O}_3{)}_2$ an obtained in solid state.
• D. $Be{F}_2$ is water soluble but $Ca{F}_2$ is water insoluble.

Answer 1

The correct option is A $KHC{O}_3$ is less soluble in water than $NaHC{O}_3$.

using Fazan's rule we can say that $KHC{O}_3$ is less soluble in water than $NaHC{O}_3$

Calcium oxalate is an ionic compound with the chemical formula $Ca{C}_2{O}_4$ and a salt of oxalic acid. It's highly insoluble and dissolves poorly in water. One method for dissolving calcium oxalate in the lab is the application of a compound called ethylenediaminetetraacetic acid or EDTA. EDTA is highly effective at binding the calcium ions and thereby decreasing the concentration of calcium in solution, shifting the reaction equilibrium so that more calcium oxalate will dissolve.

$NaHC{O}_3$ is stable to heat and normal temperature hence isolated as a solid.

However, $Ca(HC{O}_3{)}_2$ is not stable at these temperatures and hence is isolated from water, also bicarbonates of alkaline earth metals are reactive with atmospheric $C{O}_2$ leading to formation of $CaC{O}_3$.

Hydration energy decreases down the group ,so solubility decreases down the group