Question

3 C2H5OH + PCl3 → 3 C2H5Cl + H3PO3 If a chemist starts with 105.0 g of ethanol and 135.65 g of phosphorus trichloride, then what is the limiting reagent?

Answer 1

here we look
3mole of C2H5OH react with 1mole of PCl3
i.e 3x46gm C2H5OH react with (106.5+31) gm PCl3
so, 138gm---------------137.5gm
also, 1gm--------------137.5/138gm
also , 105gm ------------(137.5/138)x105gm
here we look
( 137.5/138)x105gm <135.65gm
so C2H5OH react fully then reaction stopped hence only PCl3 present
hence C2H5OH is limiting reagent