In a student experiment, a constant-volume gas thermometer is calibrated in liquid nitrogen (−196°c ) and in boiling ethyl alcohol (77°c). the separate pressures are 0.349 atm and 1.634 atm. hint: use the linear relationship p = a + bt, where a and b are constants. (a) what value of absolute zero does the calibration yield?

Respuesta :

The given linear equation is:

[tex]P=a+bt[/tex]

Determine the value of a and b (constants) by plug in the values of pressure and temperature.

[tex]P_{1}[/tex] (Pressure of liquid nitrogen) =[tex]0.349 atm[/tex]

[tex]T_{1}[/tex] (Temperature of liquid nitrogen) =[tex]-196^{0}C[/tex]

[tex]P_{2}[/tex] (Pressure of ethyl alcohol) =[tex]1.634 atm[/tex]

[tex]T_{2}[/tex] (Temperature of ethyl alcohol) =[tex]77^{0}C[/tex]

Put above values in given equation:

[tex]P_{1}=a+bT_{1}[/tex]

[tex]0.349 atm=a+b(-196^{0}C)[/tex]                 (1)

[tex]P_{2}=a+bT_{2}[/tex]

[tex]1.634 atm=a+b(77^{0}C)[/tex]              (2)

Subtract equation (1) from equation (2), we get the value of b

[tex]1.285 atm = b(273^{0}C)[/tex]

[tex]b = 4.7\times 10^{-3} atm/^{0}C[/tex]

Now, put the value of b in equation (1)

[tex]0.349 atm=a+(4.7\times 10^{-3}atm/^{0}C)(-196^{0}C)[/tex]    

[tex]a = (0.349) + (4.7\times 10^{-3}atm/^{0}C)(196^{0}C)[/tex]

[tex]a =921.549\times 10^{-3} atm[/tex]

Now, at absolute zero, Pressure is equal to zero.

Absolute temperature = [tex]T_{o} =-\frac{a}{b}[/tex]

[tex]T_{o} =  -\frac{921.549\times 10^{-3} atm}{4.7\times 10^{-3} atm/^{0}C}[/tex]

= [tex]-196.074 ^{0}C[/tex]

Thus, absolute zero = [tex]-196.074 ^{0}C[/tex]