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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: loz.xoxo on April 06, 2013, 01:20:42 pm

Title: Organic chem question
Post by: loz.xoxo on April 06, 2013, 01:20:42 pm: Hey guys!
Organic chemistry question here:

A mixture contains several different organic liquids all of which boil at temperatures greater than 50^oC. The compounds present in the mixture are separated. Compound X is analysed as follows.

Compound X is vapourised. At a temperature of 120^oC and a pressure of 115 kPa, a 0.376g sample of the vapour occupies 124mL.
a) Calculate the molar mass, in gmolL-1, of compound X.

Any takers?? All my calculations look wrong when I do them... Haha :)
Title: Re: Organic chem question
Post by: Mr. Study on April 06, 2013, 01:36:11 pm: My chem might be rusty but here goes.

$<br />\begin{align}<br />pV&=nRT \\<br />n&=\frac{pV}{RT} \\<br />&=\frac{115 \times 0.124}{8.31 \times (120+273)} \\<br />&= 0.00436642446 \\<br />n&=\frac{m}{M} \\<br />M(Molar Mass)&= \frac{m}{n} \\<br />&=\frac{0.376}{0.00436642446} \\<br />&= 86.1116 \\<br />\end{align}<br />$

But our lowest sig. figs was to 3 decimal places, so 86.1

EDIT: Sorry for the Latex ... I have no idea what is wrong . Oh and I wasn't too good with sig. figs ... so ... >_<

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