Answer:
3 Cr²⁺(aq) + 2 PO₄³⁻(aq) ⇄ Cr₃(PO₄)₂(s)
Explanation:
When aqueous solutions of chromium(II) iodide and sodium phosphate are combined, solid chromium(II) phosphate and a solution of sodium iodide are formed. The molecular equation is:
3 CrI₂(aq) + 2 Na₃PO₄(aq) ⇄ Cr₃(PO₄)₂(s) + 6 NaI(aq)
The full ionic equation includes all the ions and the molecular species.
3 Cr²⁺(aq) + 6 I⁻(aq) + 6 Na⁺(aq) + 2 PO₄³⁻(aq) ⇄ Cr₃(PO₄)₂(s) + 6 Na⁺(aq) + 6 I⁻(aq)
The net ionic equation includes only the ions that participate in the reaction and the molecular species.
3 Cr²⁺(aq) + 2 PO₄³⁻(aq) ⇄ Cr₃(PO₄)₂(s)
I would say that the approximate age of the artifact would be 13.8/15.3 x 5715=5154 years old assuming that the disintegration rate of the artifact is proportional to the present disintegration rate and to the half-life age.
Q(heat)= MC delta T
M=mass
c= specific heat capacity
delta T= change in temperature
M=density x volume which is = 1700ml x 1.0g/ml =1700g
change in temperature= 373k-295k=78 K
specific heat capacity for water is 4.186 j/g
heat is therefore= 1700g x 4.186j/g x 78k=555063.6j or 555.0636Kj