Question

Determine the concentrations of BaBr2, Ba2 , and Br– in a solution prepared by dissolving 1.18 × 10–4 g BaBr2 in 1.00 L of water. Express all three concentrations in molarity. Additionally, express the concentrations of the ionic species in parts per million (ppm).

Answer 1

Supposing complete ionization: 
BaBr2 → Ba{2+} + 2 Br{-} 

(2.23 × 10^–4 g BaBr2) / (297.135 g BaBr2/mol) / (2.00 L) = 3.75 × 10^-7 mol/L BaBr2 

(3.75 × 10^-7 mol/L BaBr2) x (1 mol Ba{2+} / 1 mol BaBr2) = 3.75 × 10^-7 mol/L Ba{2+} 

(3.75 × 10^-7 mol/L BaBr2) x (2 mol Br(-} / 1 mol BaBr2) = 7.50 × 10^-7 mol/L Br{-}