Question

Potassium carbonate is not prepared by :

• A. Solvay process
• B. Le-Blanc process
• C. Prechts process
• D. None of these.

Answer 1

Answer: (A)

Solvay process

Answer 2

(1) KHCO3 obtained as intermediate is water soluble. So it cannot be separated for obtaing K2CO3 by calcination in Solvay process.

(2) Le-Blanc process :

KCl + H2SO4$\longrightarrow$KHSO4 + HCl ; KHSO4 + KCl$\longrightarrow$K2SO4 + HCl

K2SO4 + CaCO3 + 2C $\longrightarrow$K2CO3 + CaS + 2CO2

(3) Prechts process :

(1) 2KCl + 3(MgCO3. 3H2O) + CO2 $\longrightarrow$ 2(Mg CO3. KHCO3. 4H2O) + MgCl2

(2) 2(MgCO3. KHCO3. 4H2O) $\overset{\quad 140^{0}C\quad}{\rightarrow}$2Mg CO3 $\downarrow$+ K2CO3 + 9H2O + CO2.