Math Problem Statement

An ideal gas undergoes an isothermal expansion from an initial volume of 1m^3 to a final volume of 3m^3 at a constant temperature of 300K. The initial pressure is 200 kPa. Calculate the work done by the gas during the expansion.

Solution

In an isothermal process for an ideal gas, the work done by the gas can be calculated using the following formula:

W=nRTln(VfVi)W = nRT \ln\left(\frac{V_f}{V_i}\right)

where:

  • WW is the work done by the gas,
  • nn is the number of moles of the gas,
  • RR is the ideal gas constant (R=8.314J/mol\cdotpKR = 8.314 \, \text{J/mol·K}),
  • TT is the constant temperature,
  • VfV_f is the final volume, and
  • ViV_i is the initial volume.

Since the number of moles nn is not given directly, we can use the ideal gas law to find it. The ideal gas law is:

PV=nRTPV = nRT

At the initial conditions (Pi=200kPaP_i = 200 \, \text{kPa}, Vi=1m3V_i = 1 \, \text{m}^3, and T=300KT = 300 \, \text{K}), we can rearrange the ideal gas equation to solve for nn:

n=PiViRTn = \frac{P_i V_i}{RT}

Substituting the known values:

n=200×103Pa×1m38.314J/mol\cdotpK×300Kn = \frac{200 \times 10^3 \, \text{Pa} \times 1 \, \text{m}^3}{8.314 \, \text{J/mol·K} \times 300 \, \text{K}}

Now, we can compute the value of nn, and then use that to calculate the work done during the isothermal expansion. Let's proceed with the calculation.The number of moles of the gas is approximately 80.19mol80.19 \, \text{mol}.

The work done by the gas during the isothermal expansion is approximately 219,722.46J219,722.46 \, \text{J} (or 219.72 kJ).

Would you like more details or have any further questions?

Here are 5 related questions to explore:

  1. How would the work done change if the final volume was increased further?
  2. How does the internal energy of an ideal gas behave during an isothermal process?
  3. What is the significance of the natural logarithmic relationship in the work equation?
  4. How would the process differ if it were an adiabatic expansion instead of isothermal?
  5. How can you calculate the heat transfer in an isothermal process?

Tip: In an isothermal process, the temperature remains constant, meaning any work done by the gas is exactly equal to the heat absorbed.

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Math Problem Analysis

Mathematical Concepts

Thermodynamics
Isothermal Processes
Logarithmic Functions

Formulas

W = nRT ln(Vf / Vi)
Ideal Gas Law: PV = nRT
n = (Pi * Vi) / (R * T)

Theorems

First Law of Thermodynamics

Suitable Grade Level

Undergraduate Physics (Thermodynamics)