Q.
When CO2(g) is passed over red hot coke it partially gets reduced to CO(g). Upon passing 0.5L of CO2(g) over red hot coke, the total volume of the gases increased to 700mL. The composition of the gaseous mixture at STP is
2916
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Solution:
CO2+C→2CO
Stoichoimetry ratio is 1:2
AT STP,P=1 atm, r=273K,R=0.0821
Initial moles of CO2.n(CO2 initial) =RTPV =0.0821×2731×0.5=0.022 mole
In final mixture no. of moles; n(CO2/CO mixture) =0.0821×2731×0.5=0.031
Increase in volume is by =0.031—0.022 =0.009 mole of gas
Final no. of moles of CO i.e. n(COfinal) n(COfinal)=2n(CO2initial)−n(CO2final) =2(0.002−n(CO2final))...(i) n(COfinal)=0.044−2n(CO2final)...(ii) ∴ Now, n(COfinal)+n(COfinal)=0.031 n(CO2final)=0.031−n(COfinal)...(iii)
Substituting (ii) in eq. (i) n(COfinal)=0.004−2[0.031−n(COfinal)] n(COfinal)=0.044−0.062+2n(COfinal) n(COfinal)=0.018mol.
Volume of CO=V=PnRT=10.018×0.0821×273 =0.40Litre
and volume of CO2=0.7litre−0.4litre =0.3litre ∴CO2=300mL,CO=400mL