Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: owlpower on February 27, 2018, 09:30:13 AM
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Q: Mercury is made by roasting cinnabar in quicklime at 600oC and then condensation of the released mercury vapor. Calculate the vapor pressure of the condensed mercury at 300oC given that heat of vaporization of mercury is 296J/g and the vapor pressure of mercury at 25.0oC is 2.56 X 10-3 torr. How many atoms of mercury are present in mercury vapour at 300oC if the reaction is conducted in a closed 15L container?
Hi all, please offer some tips on solving this question. I have been spending a long time on it to no avail.
I used PV = nRT to calculate mols of Mercury, from 25oC,15L and 2.56 X 10-3 torr. From there, I simple used the n value to calculate P again with the temperature at 300oC but apparently I am wrong.
Furthermore, what is the use of 296J/g? I am unable to link it to the question.
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How do you determine the vapor pressure above a liquid at temperature 2 when you know it at temperature 1?
(Hint: you assume the heat of vaporization is independent of temperature).
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You should think about phase equilibrium:
1) Which are the phases in equilibrium?
2) Which equation relates the pressure with temperature in the phase equilibrium context?
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How do you determine the vapor pressure above a liquid at temperature 2 when you know it at temperature 1?
(Hint: you assume the heat of vaporization is independent of temperature).
I do not really know how I should use the heat of vapourisation, but my guess is from 2.065x10^-6 mols of Hg, I multiply by 200.59 to get 4.14x10^-4g?
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Look up Claudius Clapeyron equation.