Would a reaction occur? if so, how would it go, [iron(III) chloride(aq) + cesium phosphate(aq)]?

Yes. A reaction will occur. This is a "classic" double replacement reaction. The "indicator" of a reaction is the formation of an insoluble precipitate. Both of the reactants are soluble in water and dissociate into ions. When combined, iron (III) ions will combine with phosphate ions to produce an insoluble precipitate, while cesium ions and chloride will remain in solution since CsCl is soluble in water. The key to predicting the outcome are the solubility rules, like these, courtesy of the North Carolina testing program:Soluble:• All Nitrates, Acetates, Ammonium, and Group 1 (IA) salts• All Chlorides, Bromides, and Iodides, except Silver, Lead, and Mercury(I)• All Fluorides except Group 2 (IIA), Lead(II), and Iron(III)• All Sulfates except Calcium, Strontium, Barium, Mercury, Lead(II), and SilverInsoluble (0.10 M or greater):• All Carbonates and Phosphates except Group 1 (IA) and Ammonium• All Hydroxides except Group 1 (IA), Strontium, Barium, andAmmonium• All Sulfides except Group 1 (IA), 2 (IIA), and Ammonium• All Oxides except Group 1 (IA)FeCl3(aq) + Cs3PO4(aq) --> FePO4(s) + 3CsCl(aq)... Show More

First consider the various possible reduction/oxidations possible [1]. Conclude it is not a redox rexn. Cs+ + e → Cs + e- Fe(III) + e- → Fe(II) cannot happen under the conditions so Fe(III) and Cs(I) happy to be together. I then look at solubility products and what do I find:iron(III) phosphate FePO4 1.3 x 10-22With experience you know the result before you start: M3+ A3- ions have large lattice energies and hence are usually insoluble. I leave you to fill in the details.... Show More