# When 2.00 L of 1.00 M of AgNO_3 and 1.25 L of 1.00 M of CaI_2 fully react, what is the molarity of Ca^2+?

Jun 24, 2017

For $2 A g N {O}_{3} \left(a q\right) + C a {I}_{2} \left(a q\right) \rightarrow 2 A g I \left(s\right) \downarrow + C a {\left(N {O}_{3}\right)}_{2} \left(a q\right)$

#### Explanation:

The calcium ion, $C {a}^{2 +}$, which is present in solution as (probably) ${\left[C a {\left(O {H}_{2}\right)}_{6}\right]}^{2 +}$, remains in solution, and expresses its concentration fully because it does not precipitate....

$\text{Moles of}$ $C {a}^{2 +} = 1.25 \cdot L \times 1.00 \cdot m o l \cdot {L}^{-} 1 = 1.25 \cdot m o l$.

The volume of solution is $\left(2.00 + 1.25\right) \cdot L = 3.25 \cdot L$

And thus concentration of calcium ion is............

$\frac{1.25 \cdot m o l}{\left(2.00 + 1.25\right) \cdot L} = 0.385 \cdot m o l \cdot {L}^{-} 1. \ldots . .$

Of course, the silver ion precipitates as a fine yellow powder of $A g I$.........