The previous questions concerned a solution prepared by you (as lab assistant). This question asks you to express the concentration in a different way. In water chemistry it is often useful and convenient to describe the concentration of phosphorus in the water without regard to the molecular package it is in. For example, orthophosphate (PO43-) is the form most readily taken up by algae to promote rapid growth, but other forms, such as diphosphate P20-4- can be converted by natural processes to orthophosphate, thus also contributing to the potential for algae blooms or other adverse effects of having too much phosphorus in the water. Organic phosphorus (e.g., bonded in a strand of DNA from a dead bacteria) will take longer to become available, but can also contribute to cellular growth. Since these other forms of phosphorus can eventually contribute to the problem, for some studies it makes sense to just express the concentration of P, as if it makes no difference that it is connected to oxygen atoms, or in a polyphosphate molecule, or in a large organic molecule. In the lab you would determine the total P concentration by first "digesting" the sample to convert all phosphorus into a form that can be measured by your test. On the other hand, if you know the chemicals that are in your sample, you can convert from conventional expressions of concentration to mg/L "as P" by recognizing the stoichiometric relationships between the actual chemical and the phosphorus atom or atoms. The atomic mass of "P" is 30.97. What is the concentration in mg/L "as P" of the solution prepared from 0.656 g Na3PO4 added to 1.00 L water? 124 0.124 0.12398 123.98