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Chemistry 10 Online
OpenStudy (dls):

Help please!

Parth (parthkohli):

@.Sam.

OpenStudy (dls):

Vapour pressure of Methyl alcohol and ethyl alcohol solutions is represented by \(P=115_(x_a)+140\) where \(x_a\) is the mole fraction of Methyl alcohol.The value of \[\LARGE \lim_{x_a \rightarrow 0} \frac{{P_b}^0}{x_B} ~=?\]

Parth (parthkohli):

@Preetha

OpenStudy (dls):

Just a random attempt: \[\Large P=115x_a+140=P_a \times X_A + P_b \times X_B\] \[\Large \frac{115x_a}{(x_B)^2}+\frac{140}{(x_B)^2}=\frac{P_a \times X_A}{(x_B)^2} +\frac{(P_B)^0}{X_B}\] I divided by X_B squared now I think xa terms will be 0 due to the limit

OpenStudy (dls):

140/Xb^2=Pb/Xb is what I'm left with,dunno if im going in the right direction

OpenStudy (dls):

\[\Large X_B=\frac{\frac{M_{Ethanol}}{46}}{\frac{M_{Methaol}}{32}}\] I don't think neglecting Xb in denominator would cause much effect,approximately I need this value not sure about masses now.

OpenStudy (shubhamsrg):

final ans = 140 ? is it? :|

OpenStudy (dls):

yes nvm

OpenStudy (shubhamsrg):

hmm

OpenStudy (dls):

?

OpenStudy (shubhamsrg):

what? it was incorrect right? :O

OpenStudy (shubhamsrg):

ohh :| let me show my work

OpenStudy (dls):

I have options though 255 115 135 140

OpenStudy (shubhamsrg):

P = 115 xa + 140 = Pa xa + Pb (1- xa) = xa ( Pa - Pb) + Pb on comparison, Pb = 140 and Pa =255 when xa -> 0 , xb -> 1 so my guess would be ans is 140

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