Question

What is the maximum amount of P2O5 that can theoretically be made from 161 g of P4 and excess oxygen? I got 2.60 mol

What is the maximum amount of P2O5 that can theoretically be made from 176 g of O2 and excess phosphorus? 2.20 mol

Last is What is the percent yield if the actual yield from this reaction is 256 g ?

Answer 1

The balanced equation is P₄ + 5O₂ 2P₂O₅

Molar mass of P₄ = 4xAt.mass of P = 4x31 = 124 g/mol

Molar mass of P₂O₅ = (2xAt.mass of P ) + ( 5xAt.mass of O )

                              = (2x31) + (5x16)

                              = 142 g/mol

According to the balanced equation ,

1 mole of P₄ produces 2 moles of P₂O₅

                          OR

1x124 g of P₄ produces 2x142 g of P₂O₅

161 g of P₄ produces M g of P₂O₅

M = ( 161 x 2x142) / (1x124)

   = 368.7 g of P₂O₅

Therefore the maximum amount of P₂O₅ formed is 368.7 g

percent yield = ( actual yield / theoretical yield) x 100

                    = ( 256 / 368.7 ) x100

                    = 69.4 %

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According to the balanced equation ,

1 mole of P₄ produces 2 moles of P₂O₅

                          OR

1x124 g of P₄ produces 2x142 g of P₂O₅

176 g of P₄ produces M g of P₂O₅

M = ( 176 x 2x142) / (1x124)

   = 403.1 g of P₂O₅

Therefore the maximum amount of P₂O₅ formed is 403.1 g

percent yield = ( actual yield / theoretical yield) x 100

                    = ( 256 / 403.1 ) x100

                    = 63.5 %