Asked by Eliz
Question: A certain sample of phosphate rock contains 26.26% P2O5. A .5428 gram sample is analyzed by percipitating MgNH4PO4*6H2O and heating it strongly to form Mg2P2O7. compute the mass of Mg2P2O7.
I'm not entirly sure what to do. Do you set up an equation?
I'm not entirly sure what to do. Do you set up an equation?
Answers
Answered by
DrBob222
You may want to write equations but it isn't necessary.
I would convert 0.5428 g sample to g P2O5.
0.5428 x 0.2626 = ??
Then ?? x (1 mol P2O5/molar mass P2O5) converts that to say x mols P2O5.
If we then recognize that 1 mole P2O5 must be present to make 1 mole Mg2P2O7, then x mol P2O5 x (1 mol Mg2P2O7/1 mole P2O5) x (molar mass Mg2P2O7/1 mol Mg2P2O7) should give grams Mg2P2O7. Check my work. There is an easier way to do this but it isn't taught anymore. The OLD way (when I was a student) was to use a gravimetric factor. That converts directly as
0.5428 x 0.2626 x (molar mass Mg2P2O7/molar mass P2O5) = ??
I get something like 0.22 something.
I would convert 0.5428 g sample to g P2O5.
0.5428 x 0.2626 = ??
Then ?? x (1 mol P2O5/molar mass P2O5) converts that to say x mols P2O5.
If we then recognize that 1 mole P2O5 must be present to make 1 mole Mg2P2O7, then x mol P2O5 x (1 mol Mg2P2O7/1 mole P2O5) x (molar mass Mg2P2O7/1 mol Mg2P2O7) should give grams Mg2P2O7. Check my work. There is an easier way to do this but it isn't taught anymore. The OLD way (when I was a student) was to use a gravimetric factor. That converts directly as
0.5428 x 0.2626 x (molar mass Mg2P2O7/molar mass P2O5) = ??
I get something like 0.22 something.