Question

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10. Consider each of the following pairs of aqueous solutions being mixed. On the basis of the solubility rules: Either .Write a full balanced chemical equation for the double displacement reaction that takes place indicating the precipitate formed by adding the (s) state symbol in the equation, and using (aq) state symbols where appropriate, AND write both the Complete and Net Ionic Equation including the state symbols. SO • If NO precipitate (solid) forms, write NO REACTION. a. Potassium phosphate and Cobalt(II) nitrate b. KOH and NaNO. C. SrCl and Lias modo

Answer 1

A double displacement reaction is a chemical process involving the exchange of bonds between two non-reacting chemical species which results in the creation of products with similar or identical bonding affiliations. This reaction is represented by the general scheme:

A-B + C-D → A-D + C-B, provided A-B are C-D are strong electrolytes i.e. in aqueous solution they fully dissociate in their cations and anions.

When one of two reactant compounds is insoluble it is termed as a double decomposition reaction.

A) Potassium Phosphate (K₃PO₄) and Cobalt Nitrate (Co(NO₃)₂) are mixed.

First, remember a Pneumonic, All phosphates(alkali metals) are soluble in acid (insoluble in alkali) and all alkali metal phosphates are soluble in any solvent.

2 K₃PO₄ (aq) + 3 Co(NO₃)₂ (aq) = 6 KNO₃ (aq) + 2 Co₃(PO₄)₂ (s) , just double displacement reaction

Net ionic: 2 PO₄^3-(aq) + 3 Co²⁺(aq) = Co₃(PO₄)₂ (s)

B) KOH (aq) + NaNO₃ (aq) = KNO₃(aq) + NaOH (aq) , KOH is better base than NaOH because of big size of K and so easily gives the OH^- easily.

  All are soluble in water, all are strong electrolytes.

As per question here is NO REACTION.

Left ionic reaction:- K⁺ + OH^- + Na⁺ + NO₃^-

Right ionic reaction:- K⁺ + NO₃^- + Na⁺ + OH^-

No net ionic Reaction as the left terms are cancelling the right terms. This means the solution contains these four ions just. Nothing else is happening.

C) SrCl₂(aq) + Li₂SO₄ (aq) = SrSO₄(s) + 2 LiCl (aq) , ions are just exchanging

Net ionic reaction:- Sr²⁺(aq) + SO₄^2-(aq) = SrSO₄(s)

   Strontium ion is big in size and comparable to Sulphate ion and the lattice energy is very high so that the Strontium Sulphate is insoluble in water. Strontium Chloride is quite soluble as Cl^- has a smaller size compare to Sulphate ion and so Lattice energy is not so high to make it insoluble in water. LiCl has partial covalent and partial ionic character due to the polarization of Chloride ion by Lithium-ion. Li⁺ has high hydration energy (due to smaller in size) and so LiCl has enough solvation energy to overcome the moderate lattice energy of LiCl (Li ion and Cl ion are not so close in size matching and that's why LiF is highly insoluble in water though both ions lithium and fluoride has high hydration energy).