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1 Physics -- First Law of Thermodynamics

What do you mean by isothermal process. Derive relation to find work done by gas expanded from pressure ′P1′ to ′P2′ at constant temperature ′T′. If 5 moles of gas at 1 atm is expanded from 50 liter from 5 liter at constant temperature of 20 C. find the work done by the gas.

What do you mean by isothermal process. Derive relation to find work done by gas expanded from pressure ′P1′ to ′P2′ at constant temperature ′T′. If 5 moles of gas at 1 atm is expanded from 50 liter from 5 liter at constant temperature of 20 C. find the work done by the gas.

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A thermodynamic process in which the temperature of the system remains constant is defined as isothermal process.

Work done by Gas from P1 to P2 at Constant Temperature


 If 5 moles of gas at 1 atm is expanded from 50 liter from 5 liter at constant temperature of 20 C. find the work done by the gas.

Solution:

n = 5

P1 = 1 atm

V1 = 50 liter

V2 = 5 liter

T = 20oC = (273 + 20) K = 293 K

At constant temperature,

Work done = nRT ln(V2/V1)

= (5 * 8.314 * 293) ln(5/50)

= - 28 kJ

The negative sign indicates that the work is done on the gas.

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