Final answer:
The composition of the salt that precipitates out when mixing solutions of Na+, PO4^3-, V3+, and Cl- can be determined using solubility rules. In this case, VPO4 is the insoluble compound that will precipitate out.
Step-by-step explanation:
When mixing solutions containing the ions Na+, PO43-, V3+, and Cl-, we can use solubility rules to determine the composition of the salt that precipitates out of the solution. By referring to Table 4.1 (or the solubility guidelines), we can identify which combinations of ions will result in an insoluble compound. For example, NaCl is highly soluble, so it will remain in solution. However, V3+ and PO43- can form an insoluble salt known as VPO4. Therefore, the composition of the salt that will precipitate out is VPO4.