Tag: isothermal and adiabatic processes

Quizzes (2) Questions (144)

Questions Related to isothermal and adiabatic processes

Multiple choice principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

Equal volumes of monoatomic and diatomic gases of same initial temperature and pressure are mixed. The ratio of the specific heats of the mixture ($C _p/C _v$) will be

  1. $1.53$

  2. $1.52$

  3. $1.5$

  4. $1$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$C _p$ for a gas is given as $(1+\displaystyle\dfrac{f}{2})R$ and $C _v$ is given as $\displaystyle\dfrac{f}{2}R$. Here f is the degree of freedom. 


For monoatomic gas it is 3 and for a diatomic gas it is 5. 

Thus, we get $C _p$ for the mixture as $\displaystyle\dfrac{5}{2}R+\dfrac{7}{2}R=6R$ and $C _v$ is given as $\displaystyle\dfrac{3}{2}R+\dfrac{5}{2}R=4R$.

Thus, the ratio $\displaystyle\dfrac{C _p}{C _v}$ is given as $\displaystyle\dfrac{3}{2}=1.5$

Multiple choice principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

The quantity of heat (in J) required to raise the temperature of $1.0\, kg$ of ethanol from $293.45\, K$ to the boiling point and then change the liquid to vapor at that temperature is closest to 
[Given : Boiling point of ethanol $351.45\, K$
              Specific heat capacity of liquid ethanol $2.44\, J\, g^{-1}\, K^{-1}$
               Latent heat of vaporization of ethanol $855\, J \, g^{-1}$]

  1. $1.42\, \times 10^2$

  2. $9.97\, \times 10^2$

  3. $1.42\, \times 10^5$

  4. $9.97\, \times 10^5$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heat to raise temperature: Q1 = m * c * delta T = 1000g * 2.44 J/gK * (351.45 - 293.45)K = 1000 * 2.44 * 58 = 141,520 J. Heat to vaporize: Q2 = m * L = 1000g * 855 J/g = 855,000 J. Total Q = 141,520 + 855,000 = 996,520 J, which is approximately 9.97 * 10^5 J.

Multiple choice principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

Which of the following statements are incorrect?
I. If $Q > 0$, heat is added to the system.
II. If $W > 0$, work is done by the system.
III. If $W = 0$, work is done by the system.

  1. II and III

  2. I, II and III

  3. I and II

  4. I and III
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

I is correct (heat added). II is correct (work done by system). III is incorrect because if W=0, no work is done by the system; the system is at constant volume.