2. One mole of a monatomic ideal gas undergoes a reversible expansion at constant pressure, during which the entropy of the gas increases by 14.41 J/K and the gas absorbs 6236 J of thermal energy. Calculate the initial and final temperatures of the gas.

Respuesta :

Answer:

The initial and final temperatures of the gas is 300 K and 600 K.

Explanation:

Given that,

Entropy of the gas = 14.41 J/K

Absorb gas = 6236 J

We know that,

[tex]ds=\dfrac{dQ}{dt}[/tex]

At constant pressure,

[tex]dQ=C_{p}dt[/tex]

[tex]\Delta s=\int_{T_{1}}^{T_{2}}{\dfrac{C_{p}dT}{T}}[/tex]

[tex]\Delta s=C_{p}ln\dfrac{T_{2}}{T_{1}}[/tex]

Put the value into the formula

[tex]14.41=2.5\times8.3144(ln\dfrac{T_{2}}{T_{1}})[/tex]

[tex]\dfrac{14.41}{2.5\times8.3144}=ln\dfrac{T_{2}}{T_{1}}[/tex]

[tex]0.693=ln\dfrac{T_{2}}{T_{1}}[/tex]

[tex]ln2=ln\dfrac{T_{2}}{T_{1}}[/tex]

[tex]T_{2}=2T_{1}[/tex]...(I)

We need to calculate the initial and final temperatures of the gas

Using formula of energy

[tex]\Delta Q=C_{p}\Delta T[/tex]

Put the value into the formula

[tex]6236=2.5\times8.3144(T_{2}-T_{1})[/tex]

[tex]6236=20.786(T_{2}-T_{1})[/tex]

[tex]T_{2}-T_{1}=\dfrac{6236}{20.786}[/tex]

[tex]T_{2}-T_{1}=300[/tex]

Put the value of T₂

[tex]2T_{1}-T_{1}=300[/tex]

[tex]T_{1}=300\ K[/tex]

Put the value of T₁ in equation (I)

[tex]T_{2}=2\times300[/tex]

[tex]T_{2}=600\ K[/tex]

Hence, The initial and final temperatures of the gas is 300 K and 600 K.