Question

Equimolar solutions of the following were prepared in water separately. Which one of the solutions will record the highest pH ?

• A. $SrCl_2$
• B. $BACl_2$
• C. $MgCl_2$
• D. $CaCl_2$

Answer 1

Answer: (B)

$BACl_2$

Answer 2

All salts are soluble in water and give strong acid
and weak base
$SrCl_2 + 2H_2O \longrightarrow Sr (OH)_2 + 2HCl$
$BaCl_2 + 2H_2 O \longrightarrow Ba(OH)_2 + 2 HCl$
$MgCl_2 + 2H_2O \longrightarrow Mg(OH)_2 + 2HCl$
$CaCl_2 + 2H_2 O \longrightarrow Ca(OH)_2 + 2HCl$
The basic nature of alkaline earth metals is
generally increases from Be to Ra. Thus, the order of
basic nature of these hydroxides is
$Mg(OH)_2 < Ca(OH)_2 < Sr(OH)_2 < Ba(OH)_2$
Hence, pH is highest for $BaCl_2$. (As pH increases
with basic nature)