Question #90897

What is the limiting reagent when 0.50 mol of Cr and 1.0 mol of H3PO4 react according

to the following chemical equation?

2Cr + 2H3PO4 → 2CrPO4 + 3H2

If 0.20 mol of CrPO4 is recovered from the reaction described above, what is the percent yield?

to the following chemical equation?

2Cr + 2H3PO4 → 2CrPO4 + 3H2

If 0.20 mol of CrPO4 is recovered from the reaction described above, what is the percent yield?

Expert's answer

Limiting reagent is reagent that is in a smaller molar amount in a chemical reaction. Limiting reagent limits the amount of products that can be made. In the reaction shown above the limiting reagent is Cr (0.50 mole < 1.0 mole).

"percent \\space yield = \\frac {actual \\space yield }{theoretical \\space yield} \\cdot 100 \\%"

"actual \\space yield = 0.20 \\space mol \\cdot \\frac {146.97 g\/mol} {1mol} = 29 g"

Calculate theoretical yield:

"mol \\space of \\space CrPO_4 = 0.50 \\space mol \\space Cr\n \\cdot \\frac {2mol \\space CrPO_4}{2 mol \\space Cr}=0.50 mol"

"theoretical \\space yield = mass \\space of \\space CrPO_4 = 0.50 \\cdot 146.97 \\space g\/mol = 73 \\space g"

"percent \\space yield = \\frac {29 g}{73g} \\cdot 100 \\% =40 \\%"

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