{"knowledge_schema": {"broad_category": "Chemistry \u2192 Solutions \u2192 Concentration Calculations", "refinement": "This problem involves calculating the concentration of specific ions in a solution based on the mass of solutes and their molar masses.", "specific_scope": "The focus is on determining the concentration of orthophosphate ions (PO4^3-) in a buffered solution containing KH2PO4 and Na2HPO4\u25cf2H2O.", "goal": "Calculate the concentration of orthophosphate ions in molarity (M) from the given masses of the compounds and their respective molar masses."}, "summary": "This problem is centered around chemistry, specifically the calculation of ion concentration in a solution. It requires determining the concentration of orthophosphate ions from the masses of potassium dihydrogen phosphate (KH2PO4) and disodium hydrogen phosphate dihydrate (Na2HPO4\u25cf2H2O) in a 250.00 cm\u00b3 solution. The solution involves converting the mass of each compound to moles using their molar masses and then calculating the concentration of the orthophosphate ions. The final answer is 7.12x10^-7 M, which represents the concentration of orthophosphate ions in the solution."}