# What is the mole ratio of H_2O to H_3PO_4 in the following chemical equation? P_4O_10 + 6H_2O -> 4H_3PO_4?

Mar 11, 2017

And so the molar ration is $6 : 1$, $\text{water:phosphoric acid}$.......
Note that ${P}_{4} {O}_{10}$ is a common laboratory reagent for drying halogenated reagents such as methylene chloride. Because ${P}_{4} {O}_{10}$ reacts with atmospheric water, often when you open a used bottle of phosphorus pentoxide, you see a sticky white syrup on the surface of the reagent, where atmospheric water has reacted with the oxide. When you dig down, sometimes you find the actual reagent, which should be a free-flowing powder.