High School

An ideal gas undergoes a reversible isothermal expansion at 87.1°C, increasing its volume from 1.45 L to 3.99 L. The entropy change of the gas is 36.6 J/K. How many moles of gas are present?

Provide your answer with appropriate units.

Answer :

The number of moles of gas present is given by n = (36.6 J/K) / (R ln(3.99 L / 1.45 L)).

To determine the number of moles of gas present, we need to use the formula for entropy change during an isothermal process:

ΔS = nR ln(Vf/Vi)

Where:

ΔS is the entropy change,

n is the number of moles,

R is the gas constant,

Vf is the final volume, and

Vi is the initial volume.

Given that ΔS = 36.6 J/K, Vi = 1.45 L, and Vf = 3.99 L, we can rearrange the equation to solve for n:

n = ΔS / (R ln(Vf/Vi))

Step 1: Convert temperatures from Celsius to Kelvin.

The given temperature is 87.1°C. We need to add 273.15 to convert it to Kelvin:

T = 87.1°C + 273.15 = 360.25 K

Step 2: Determine the gas constant.

The gas constant can vary depending on the units used. We can choose the appropriate gas constant based on the desired units for the number of moles.

Step 3: Calculate the number of moles.

Using the gas constant and the given values, substitute them into the equation and evaluate:

n = (36.6 J/K) / (R ln(3.99 L / 1.45 L))

Step 4: Solve for the number of moles.

Plug in the values and calculate the number of moles of gas present.

Note: Make sure to choose the appropriate gas constant (R) based on the desired units for the number of moles.

Learn more about moles from the given link: https://brainly.com/question/15209553

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