While mercury is very useful in barometers, mercury vapor is toxic. Given that mercury has a ΔHvap of 59.11 kJ/mol and its normal boiling point is 356.7°C, calculate the vapor pressure in mm Hg at room temperature, 25°C.

Respuesta :

Answer:

P = 2.65 E-3 mm Hg

Explanation:

liquid-vapor equilibrium:

⇒ ec. Clausius-Clapeyron:

  • Ln (P2/P1) = - ΔHv/R [ (1/T2) - (1/T1) ]

∴ R = 8.314 E-3 KJ/K.mol

∴ ΔHv = 59.11 KJ/mol

∴ T2 = 25°C ≅ 298 K

∴ T1 = 356.7°C = 629.7 K

normal boiling point:

∴ P = 1 atm = P1 = 101.325 KPa

vapor pressure (P2):

⇒ Ln P2 - Ln (101.325) = - (59.11 KJ/mol)/(8.314 E-3 KJ/K.mol)*[ (1/298) - (1/629.7) ]

⇒ Ln P2  - 4.618 = - (7109.694 K)*[ 1.7676 E-3 K-1 ]

⇒ Ln P2 = 4.618  - 12.567

⇒ P2 = e∧(-7.9494)

⇒ P2 = (3.5313 E-4 KPa)×(7.50062mm Hg/KPa) = 2.65 E-3 mm Hg

The vapor pressure is caused by the vaporized component of a liquid on the walls of the closed container.

A Clausis Clayperon equation's formula is as follows:

[tex]\ln \frac{P1}{P2}=-\Delta \frac{H}{R} - (\frac{1}{T1} - \frac{1}{T2})[/tex]

where

[tex]P1 = 760 \ mm Hg \\\\ \Delta H vap = 59.11 \ \frac{kJ}{mol}\\\\ R= 8.314 \frac{J}{Kmol}\\\\T1= 356.7 ^{\circ} C = 629.85\ K \\\\T2 = 25 ^{\circ} C = 298.15\ K\\\\[/tex]

putting the value into the formula:

[tex]\ln \frac{760}{P2}=-\frac{59110}{8.314}-(\frac{1}{629.8} - \frac{1}{298.15})\= 12.557\\\\\to \frac{760}{P2 }= 284076.828\\\\\to P2 = 2.675 \times 10^{-3} \ mmHg[/tex]

Therefore, the final answer is "[tex]2.675 \times 10^{-3} \ mmHg[/tex]" .

Learn more:

brainly.com/question/14739464