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An empty 149 mL flask weighs 68.322 g before a sample of volatile liquid is added. The flask is then placed in a hot (95.0°C) water bath; the barometric pressure is 740 torr. The liquid vaporizes and the gas fills the flask. After cooling, flask and condensed liquid together weigh 68.697 g. What is the molar mass of the liquid?​

Respuesta :

ardni313

MW liquid = 77.811 g/mol

Further explanation

In general, the gas equation can be written  

PV=nRT  

where  

P = pressure, atm , N/m²  

V = volume, liter  

n = number of moles  

R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m², v= m³)  

T = temperature, Kelvin  

  • mass of condensed liquid :

[tex]\tt 68.697-68.322=0.3741~g[/tex]

P = 740 torr = 0.973684 atm

V = 149 ml = 0.149 L

T = 95 °c = 95+273 = 368 K

input in formula :

[tex]\tt 0.973684\times 0.149=\dfrac{0.3741}{MW~liquid}\times 0.082\times 368\\\\MW=77.811~g/mol[/tex]

The molar mass of  liquid = 77.811 g/mol

Ideal Gas equation

[tex]PV=nRT[/tex]

where  

P = pressure, atm , N/m²  

V = volume, liter  

n = number of moles  

R = gas constant = 0.0821 Latm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m², v= m³)  

T = temperature, Kelvin  

We can calculate molar mass  from ideal gas equation,

[tex]PV=\frac{m}{M} RT[/tex]

Here M is the molar mass.

mass of condensed liquid :[tex]68.697-68.322=0.3741g[/tex]

P = 740 torr = 0.973684 atm

V = 149 ml = 0.149 L

T = 95 °c = 95+273 = 368 K

Substitute all values in the ideal gas equation as follows,

[tex]0.973684\times0.149= \frac{0.3741}{molar Mass} \times0.082\times368\\Molar mass=77.811\ g/mol[/tex]

Find more information about ideal gas equation and molar mass here,

brainly.com/question/4147359

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