If the percent yield is 82.0%,how many grams of silicon is needed to make 105 g of chromium by the reaction: 3 Si (s)+ 2 Cr₂O₃(s)→ 3 SiO₂(s)+ 4 Cr (l)? A)51.9 g B)92.2 g C)42.5 g D)34.9 g E)13.0 g

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Quizplus · Accepted Answer

To find the grams of silicon needed, first, calculate the theoretical yield of chromium from 105 g, considering the percent yield. If 82.0% yield gives 105 g of chromium, 100% would give 105 g / 0.82 = 128.05 g of Cr. Using the molar mass of Cr (51.996 g/mol) to find moles: 128.05 g / 51.996 g/mol = 2.463 moles of Cr. From the balanced equation, 3 moles of Si produce 4 moles of Cr, so for 2.463 moles of Cr, (3/4) * 2.463 moles of Si are needed = 1.84725 moles of Si. Using the molar mass of Si (28.0855 g/mol), the mass of Si needed is 1.84725 moles * 28.0855 g/mol = 51.9 g.

If the Percent Yield Is 82