Question

Many computer chips are manufactured from silicon, which occurs in nature as SiO2. When SiO2 is heated to melting, it reacts with solid carbon to form liquid silicon and carbon monoxide gas. In an industrial preparation of silicon, 156.7 kg of SiO2 is allowed to react with 78.2 kg of carbon to produce 66.2 kg of silicon.

1.) Determine the limiting reactant for the reaction.

2.) Determine the theoretical yield for the reaction.

3.) Determine the percent yield for the reaction.

Answer 1

SiO2 (s)+ C(s) -------------> Si(l) + CO2(g)

no of moles of SiO2    = W/G.M.Wt   = 156700/60   = 2611.6moles

no of moles of C          = W/G.M.Wt   = 78200/12     = 6516.6moles

from balanced equation

1 mole of SiO2 react with 1 mole of C

2611.6 moles of SiO2 react with 2611.6 moles of C is required

SiO2 is limiting reacant.

C is excess reactant

SiO2 (s)+ C(s) -------------> Si(l) + CO2(g)

1 moles of SiO2 react with C to gives 1 mole of Si

2611.6 moles of SiO2 react with C to gives 2611.6moles of Si

mass of Si = no of moles * gram atomic mass

                   = 2611.6*28   = 73124.8g >>>>>theoretical yield

percentage   = actul yield*100/theoretical yield

                    = 66200*100/73124.8   = 90.53% >>>>>answer