EXAMPLE - Equation Stoichiometry with Mixtures:
Calcium dihydrogen phosphate, Ca(H2PO4)2,
which is used in the production of triple superphosphate fertilizers, can be
formed from the reaction of phosphoric acid with apatite, Ca5(PO4)3F,
in apatite ore.
a. Remember that percentages convey a ratio that can be used as a conversion
factor (Section 8.4). Thus, 81.7% Ca5(PO4)3F in
apatite ore can be described as
This conversion factor can be used to convert between mass of ore and mass of the pure substance Ca5(PO4)3F. The following shows one way to work this problem.
= 1.61 x 105 metric tons Ca(H2PO4)2
b. For this calculation, the percentage provides a conversion
factor that converts from mass of Ca5(PO4)3F to
mass of the apatite ore.
= 4.2 x 103 kg ore