I can't draw a graph but I can describe how to do it.
____________
|
|
|
|____________
Now turn this counter clockwise 90 degrees so it looks almost like a U (looks like this, |_|, but on a larger scale.)
Place 1.3330 on the left Y axis and 1.3610 on the right Y axis, then draw a line from left to right. Now you want to determine the differences. I find drawing a diagram helps.
1.3330<---------0.02800----------1.3610
...|...................1.3541........|
.......<-----0.0210----->|<--0.00690-->
Then I've placed the 1.3541 for the sample on the graph and determined the differences between pure water and pure EtOH as well as the differences between the sample and pure water and the sample and pure EtOH.
mole fraction = 1.00 for pure water abd 1.00 for pure EtOH
1 x (0.00690/0.0280) = 0.2464 = XH2O
1 x (0.02110/0.0280) = 0.7536 = XEtOH.
I hope this helps. Sorry I couldn't draw a better diagram.
Check my work.
Multiply by 100 for mole percents.
A solution consisting of water and ethanol is found to have a refractive index of 1.3541 at 20 degrees C. The refractive indices at 20 degrees C of water and ethanol are 1.3330 and 1.3610, respectively. Determine the molar composition (in percent) of the mixture by assuming a linear relation between the refractive index and the molar composition of the mixture.
Molar composition of water: ____%
Molar composition of ethanol: ____%
I have no idea on where to begin. Please help!
1 answer