An ideal gas initially at 4.00atm and 350 K is permitted
toexpand adibatically to 1.50 times its initial volume. Findthe
final pressure and temperature if the gas is a)monoatomic;
b)diatomic with Cv=.

Respuesta :

Explanation:

It is given that initially pressure of ideal gas is 4.00 atm and its temperature is 350 K. Let us assume that the final pressure is [tex]P_{2}[/tex] and final temperature is [tex]T_{2}[/tex].

(a)   We know that for a monoatomic gas, value of [tex]\gamma[/tex] is \frac{5}{3}[/tex].

And, in case of adiabatic process,

                [tex]PV^{\gamma}[/tex] = constant              

also,         PV = nRT

So, here    [tex]T_{1}[/tex] = 350 K,    [tex]V_{1} = V[/tex],  and   [tex]V_{2} = 1.5 V[/tex]

Hence,      [tex]\frac{T_{2}}{T_{1}} = (\frac{V_{1}}{V_{2}})^{\gamma -1}[/tex]

         [tex]\frac{T_{2}}{350 K} = (\frac{V}{1.5V})^{\frac{5}{3} -1}[/tex]

          [tex]T_{2}[/tex] = 267 K

Also,   [tex]P_{1}[/tex] = 4.0 atm,   [tex]V_{1} = V[/tex],  and   [tex]V_{2} = 1.5 V[/tex]

        [tex]\frac{P_{2}}{P_{1}} = (\frac{V_{1}}{V_{2}})^{\gamma}[/tex]

        [tex]\frac{P_{2}}{4.0 atm} = (\frac{V}{1.5V})^{\frac{5}{3}}[/tex]

            [tex]P_{2}[/tex] = 2.04 atm

Hence, for monoatomic gas final pressure is 2.04 atm and final temperature is 267 K.

(b) For diatomic gas, value of [tex]\gamma[/tex] is \frac{7}{5}[/tex].

As,        [tex]PV^{\gamma}[/tex] = constant              

also,         PV = nRT

[tex]T_{1}[/tex] = 350 K,    [tex]V_{1} = V[/tex],  and   [tex]V_{2} = 1.5 V[/tex]

              [tex]\frac{T_{2}}{T_{1}} = (\frac{V_{1}}{V_{2}})^{\gamma -1}[/tex]

         [tex]\frac{T_{2}}{350 K} = (\frac{V}{1.5V})^{\frac{7}{5} -1}[/tex]

          [tex]T_{2}[/tex] = 289 K

And,   [tex]P_{1}[/tex] = 4.0 atm,   [tex]V_{1} = V[/tex],  and   [tex]V_{2} = 1.5 V[/tex]

                [tex]\frac{P_{2}}{P_{1}} = (\frac{V_{1}}{V_{2}})^{\gamma}[/tex]

        [tex]\frac{P_{2}}{4.0 atm} = (\frac{V}{1.5V})^{\frac{7}{5}}[/tex]

            [tex]P_{2}[/tex] = 2.27 atm

Hence, for diatomic gas final pressure is 2.27 atm and final temperature is 289 K.