Silicon is made by heating silica with coke: SiO2 + 2C -> Si + 2CO. If 30.0 g of SiO2 (molar mass 60 g/mol) is heated with excess coke and the yield of Si is 80%, the volume of CO produced at STP (22.4 L/mol) is

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Silicon is made by heating silica with coke: $SiO X_{2} + 2 C Si + 2 CO$ . If 30.0 g of $SiO X_{2}$ (molar mass 60 g/mol) is heated with excess coke and the yield of Si is 80%, the volume of $CO$ produced at STP (22.4 L/mol) is

n (SiO X_{2}) = 30.0/60 = 0.50

mol. At 80% yield,

n (Si) = 0.40

mol, and 2 mol

CO

form per mol of Si, so

n (CO) = 0.80

mol. Volume

= 0.80 \times 22.4 = 17.92