The reaction of Cr2O3 with sil
The reaction of Cr2O3 with silicon metal at high temperatureswill make chromium metal.
2Cr2O3(s)+3Si(s)–>4Cr(l)+3SiO2(s)
The reaction is begun with 80.00 g of Si and 147.00 g ofCr2O3.
How many grams of the excess reactant are left after thereaction is complete?
Answer:
Molar mass of Cr2O3,MM = 2*MM(Cr) + 3*MM(O)= 2*52.0 + 3*16.0= 152 g/molmass(Cr2O3)= 147.0 guse:number of mol of Cr2O3,n = mass of Cr2O3/molar mass of Cr2O3=(147.0 g)/(152 g/mol)= 0.9671 molMolar mass of Si = 28.09 g/molmass(Si)= 80.0 guse:number of mol of Si,n = mass of Si/molar mass of Si=(80.0 g)/(28.09 g/mol)= 2.848 molBalanced chemical equation is:2 Cr2O3 + 3 Si —> 4 Cr + 3 SiO22 mol of Cr2O3 reacts with 3 mol of Sifor 0.9671 mol of Cr2O3, 1.451 mol of Si is requiredBut we have 2.848 mol of Siso, Cr2O3 is limiting reagentwe will use Cr2O3 in further calculationAccording to balanced equationmol of Si reacted = (3/2)* moles of Cr2O3= (3/2)*0.9671= 1.451 molmol of Si remaining = mol initially present – mol reactedmol of Si remaining = 2.848 – 1.451mol of Si remaining = 1.397 molMolar mass of Si = 28.09 g/moluse:mass of Si,m = number of mol * molar mass= 1.397 mol * 28.09 g/mol= 39.25 gAnswer: 39.2 g
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