Question icon
Grade 12Physical Chemistry

ratio of Cp of O2 and Cv of O3 will be?? question 2): and if 3 moles of O2 is mixed with 2 molesof N2 then the value of Cp/Cv will be??

Profile image of mini yadav
10 Years agoGrade 12
Answers icon

1 Answer

Profile image of Askiitians Tutor Team
ApprovedApproved Tutor Answer1 Year ago

To determine the ratio of specific heats, Cp (heat capacity at constant pressure) and Cv (heat capacity at constant volume), for the gases involved, we need to consider the molecular structure and degrees of freedom of the gases in question. Let's break this down step by step.

Understanding Cp and Cv

Cp and Cv are important thermodynamic properties that describe how a substance responds to heat. For ideal gases, these values can be related to the number of degrees of freedom of the gas molecules. The ratio of Cp to Cv is denoted as γ (gamma).

Specific Heats of O2 and O3

For diatomic oxygen (O2), the specific heats are:

  • Cp (O2) ≈ 29 J/(mol·K)
  • Cv (O2) ≈ 21 J/(mol·K)

For ozone (O3), being a triatomic molecule, it has more degrees of freedom, which typically results in higher specific heats:

  • Cp (O3) ≈ 48 J/(mol·K)
  • Cv (O3) ≈ 39 J/(mol·K)

Calculating the Ratio for O2 and O3

To find the ratio of Cp of O2 to Cv of O3, we use the values we just mentioned:

Ratio = Cp(O2) / Cv(O3) = 29 J/(mol·K) / 39 J/(mol·K)

This simplifies to approximately:

Ratio ≈ 0.743

Analyzing the Mixture of O2 and N2

Now, let’s consider the second part of your question regarding the mixture of gases. When 3 moles of O2 are mixed with 2 moles of N2, we need to find the overall Cp/Cv ratio for the mixture.

Specific Heats of N2

For nitrogen (N2), the specific heats are:

  • Cp (N2) ≈ 29 J/(mol·K)
  • Cv (N2) ≈ 21 J/(mol·K)

Calculating the Mixture's Cp and Cv

To find the total Cp and Cv for the mixture, we can use the mole fractions of each gas:

  • Mole fraction of O2 = 3 / (3 + 2) = 3/5
  • Mole fraction of N2 = 2 / (3 + 2) = 2/5

Now, we calculate the average Cp and Cv for the mixture:

  • Average Cp = (3/5) * Cp(O2) + (2/5) * Cp(N2)
  • Average Cv = (3/5) * Cv(O2) + (2/5) * Cv(N2)

Substituting the values:

  • Average Cp = (3/5) * 29 + (2/5) * 29 = 29 J/(mol·K)
  • Average Cv = (3/5) * 21 + (2/5) * 21 = 21 J/(mol·K)

Final Ratio of Cp/Cv for the Mixture

Now, we can find the ratio:

Ratio = Average Cp / Average Cv = 29 / 21 ≈ 1.38

In summary, the ratio of Cp of O2 to Cv of O3 is approximately 0.743, and the Cp/Cv ratio for the mixture of 3 moles of O2 and 2 moles of N2 is approximately 1.38. Understanding these ratios is crucial for applications in thermodynamics and engineering, as they help predict how gases will behave under different conditions.