Problem

A solution buffered at pH 9.30 is 0.0050 M in both Ba

^{2+}

and Sr

^{2+}

. The carbonate ion concentration in the buffer is

1.0\times10^{-3}

M. Solubility products are

K_{sp}(\text{BaCO}_3)=5.1\times10^{-9}

and

K_{sp}(\text{SrCO}_3)=1.0\times10^{-10}

. Which metal ion will selectively precipitate as its carbonate under these conditions? Provide only the ion’s chemical symbol.