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One mole of a monoatomic ideal gas under...

One mole of a monoatomic ideal gas undergoes a thermodynamic process such that`V^3/T^2`= constant. Then,

A

work done by the gas is 200R when temperature of the gas is raised by 300 K

B

the specific heat of the gas in the process is `13/6R `

C

work done by the gas is 300R when temperature of the gas maised by 600 K

D

the specific heat of the gas in the process is `21/4` R

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the thermodynamic process described by the equation \( \frac{V^3}{T^2} = \text{constant} \). This indicates that the process is a polytropic process. We will derive the work done by the gas and the specific heat for this process step by step. ### Step-by-Step Solution: 1. **Identify the relationship**: Given the equation \( \frac{V^3}{T^2} = C \), we can express \( T \) in terms of \( V \): \[ T^2 = \frac{V^3}{C} \implies T = \sqrt{\frac{V^3}{C}} = \frac{V^{3/2}}{\sqrt{C}} \] 2. **Using the Ideal Gas Law**: The ideal gas law states that \( PV = nRT \). For one mole of gas (\( n = 1 \)), we have: \[ PV = RT \] Substituting for \( T \) from the previous step: \[ PV = R \cdot \frac{V^{3/2}}{\sqrt{C}} \implies P = \frac{R \cdot V^{1/2}}{\sqrt{C}} \] 3. **Finding the Polytropic Index \( x \)**: In a polytropic process, \( PV^x = \text{constant} \). We can express \( P \) in terms of \( V \): \[ P \propto V^{-x} \implies \frac{R \cdot V^{1/2}}{\sqrt{C}} \propto V^{-x} \] This implies: \[ V^{1/2 + x} = \text{constant} \] Therefore, we have: \[ 1/2 + x = 0 \implies x = -\frac{1}{2} \] 4. **Calculating the Work Done**: The work done by the gas in a polytropic process is given by: \[ W = \frac{nR \Delta T}{1 - x} \] Here, \( n = 1 \) (one mole), and substituting \( x = -\frac{1}{2} \): \[ W = \frac{R \Delta T}{1 - (-\frac{1}{2})} = \frac{R \Delta T}{1 + \frac{1}{2}} = \frac{R \Delta T}{\frac{3}{2}} = \frac{2R \Delta T}{3} \] 5. **Assuming a Change in Temperature**: Let's assume a change in temperature \( \Delta T = 300 \, K \): \[ W = \frac{2R \cdot 300}{3} = 200R \] 6. **Calculating Specific Heat**: The specific heat \( C \) for a polytropic process is given by: \[ C = \frac{R}{\gamma - 1} + \frac{R}{1 - x} \] For a monoatomic gas, \( \gamma = \frac{5}{3} \): \[ C = \frac{R}{\frac{5}{3} - 1} + \frac{R}{1 - (-\frac{1}{2})} = \frac{R}{\frac{2}{3}} + \frac{R}{\frac{3}{2}} = \frac{3R}{2} + \frac{2R}{3} \] Finding a common denominator (6): \[ C = \frac{9R}{6} + \frac{4R}{6} = \frac{13R}{6} \] ### Final Results: - The work done by the gas is \( W = 200R \). - The specific heat of the gas during this process is \( C = \frac{13R}{6} \).
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Knowledge Check

  • A certain amount of an ideal monoatomic gas undergoes a thermodynamic process such that VT^(2)= constat where V= volume of gas, T= temperature of gas. Then under process

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    B
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