Question

During lab, students mixed two solutions of soluble ions in a ceramic well to determine if a precipitate forms.
Write the dissolution reaction for the ionic solids below. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)
(a) Ca(NO3)2
(b) Na3PO4
The two solutions, when mixed, will have two cations and two anions.
(c) Based on your lab results, enter the cation and anion for which a precipitate will form. (Separate substances in a list with a comma.)
(d) Write the net precipitation reaction that occurs. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)

Answer 1

Answer:

(a) $Ca(NO_3)_2(s)\rightarrow Ca^{2+}(aq)+2NO_3^-(aq)$

(b) $Na_3PO_4(s)\rightarrow 3Na^++PO_4^{3-}$

(c) $Ca^{2+} \ and \ PO_4^{3-}$

(d) $3Ca^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Ca_3(PO_4)_2(s)$

Explanation:

Hello,

In this case, the balanced dissolution reactions are:

(a) $Ca(NO_3)_2(s)\rightarrow Ca^{2+}(aq)+2NO_3^-(aq)$

(b) $Na_3PO_4(s)\rightarrow 3Na^++PO_4^{3-}$

Moreover, when calcium nitrate and sodium phosphate react a double displacement reaction occurs, forming calcium phosphate, which is actually the precipitate due to its low solubility in water, and sodium nitrate:

$2Na_3PO_4(aq)+3Ca(NO_3)_2(aq)\rightarrow 6NaNO_3(aq)+Ca_3(PO_4)_2(s)$

Thus, the precipitate is formed by:

(c) $Ca^{2+} \ and \ PO_4^{3-}$

Finally, the net precipitation reaction shows the involved cation, anion and final product:

(d) $3Ca^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Ca_3(PO_4)_2(s)$

Regards.