Project ForgeConsider a binary mixture of methyl ethyl ketone (component 1) and toluene (component 2). At 323K, lnγ1=x2²(ψ1−ψ2+4ψ2x1), lnγ2=x1²(ψ1+ψ2−4ψ2x2). The infinite dilution activity coefficients are lnγ1^∞=0.4 and lnγ2^∞=0.2. Vapour pressures at 323K are 36.9 and 12.3 kPa. Assuming ideal vapour phase, the equilibrium pressure (in kPa) of a liquid mixture containing 90 mol% toluene is
- A19
- B18
- 16
- D15
Explanation
At infinite dilution: lnγ1^∞=ψ1−ψ2=0.4, lnγ2^∞=ψ1+ψ2=0.2, giving ψ1=0.3, ψ2=−0.1. At x1=0.1, x2=0.9: lnγ1=0.81×(0.4−0.04)=0.2916⟹γ1=1.339; lnγ2=0.01×(0.2+0.36)=0.0056⟹γ2=1.006. P=x1γ1P1sat+x2γ2P2sat=0.1×1.339×36.9+0.9×1.006×12.3≈4.94+11.13≈16.1 kPa.
Source: GATE CH 2011 (2011)
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