# A bottle of calcium bromide contains a bromide ion concentration of 0.10 mol/L. What is the concentration of the calcium bromide?

May 30, 2017

$\left[C a B {r}_{2}\right] = 0.050 \cdot m o l \cdot {L}^{-} 1$

#### Explanation:

Calcium bromide speciates in aqueous solution according to the following equation.........

$C a B {r}_{2} \left(s\right) \stackrel{{H}_{2} O}{\rightarrow} C {a}^{2 +} + 2 B {r}^{-}$

And thus for every metal ion there are necessarily two bromide ions.

Here by specification,

$\left[B {r}^{-}\right] = 0.10 \cdot m o l \cdot {L}^{-} 1$, and thus $\left[C {a}^{2 +}\right] = \frac{1}{2} \times \left[B {r}^{-}\right] = \frac{1}{2} \times 0.10 \cdot m o l \cdot {L}^{-} 1 = 0.050 \cdot m o l \cdot {L}^{-} 1$