We'll first write the chemical equation for this reaction:
"P"_4"O"_10(s) + 6"H"_2"O"(l) rarr 4"H"_3"PO"_4(aq)
Let's now find the relative number of moles of phosphoric acid ("H"_3"PO"_4) using the coefficients of the equation, and the fact that 10.0 "mol H"_2"O" react:
10.0cancel("mol H"_2"O")((4color(white)(l)"mol H"_3"PO"_4)/(6cancel("mol H"_2"O"))) = color(red)(6.67 color(red)("mol H"_3"PO"_4
Now, using the molar mass of "H"_3"PO"_4 (calculated to be 98.00 "g/mol"), let's find the theoretical mass of phosphoric acid produced:
color(red)(6.67)color(white)(l)cancel(color(red)("mol H"_3"PO"_4))((98.00color(white)(l)"g H"_3"PO"_4)/(1cancel("mol H"_3"PO"_4))) = color(blue)(653 color(blue)("mol H"_3"PO"_4
Thus, if the reaction goes to completion, there will be a yield of color(blue)(653 sfcolor(blue)("grams of phosphoric acid".
