# Pressure/Temp/Volume question

• itr
In summary, we are given an isothermal expansion of an ideal gas from a pressure of 2x10^6 N/m^2 to 2x10^5 N/m^2. We are asked to find the heat absorbed by the gas, the change in internal energy, and the entropy change if the expansion is reversible. Using the equations Q=mc(Δt), ΔE=Q-W, PV=nRT, and W=PΔV, we can solve for the values needed. Since it is an isothermal process, there is no change in temperature and therefore ΔE is equal to zero. This makes the equation ΔE=Q-W simplify to Q=W. To find the work, we use the
itr

## Homework Statement

One mole of an ideal gas at 300K expands isothermally from a pressure of 2x10^6 N/m^2 to a pressure of 2x10^5 N/m^2.

Derive the equations for, and calculate:

the heat absorbed by the gas...
the change in the internal energy of the gas...
the entropy change in the gas if it expands reversibly

## Homework Equations

Q=mc(Δt)
ΔE = Q - W
PV = nRT
W = PΔV
Another equation involving ΔE, but i am not sure what it is...

## The Attempt at a Solution

Since it is an isothermic equation, there is no Δt...which makes the ΔE equal zero(the internal energy). Since the internal energy is zero, that makes the equation ΔE=Q-W into Q=W. I am not sure how to finish the problem, because i have a change in pressure...but there is no change in temperature...

Work is just the area under a PV diagram. Draw out the diagram, label V1 and V2 (the initial and final volumes), and you'll see what the area is.

how do i know what the change in volumes are? all i know is there is a pressure decrease, which could mean anything...unless i am missing something

## 1. What is the relationship between pressure, temperature, and volume?

The relationship between pressure, temperature, and volume is known as the Ideal Gas Law, which states that the product of pressure and volume is directly proportional to the product of the number of moles of gas and the temperature, assuming all other factors remain constant.

## 2. How does changing the pressure affect the temperature and volume of a gas?

If the pressure of a gas increases, the temperature will also increase, and the volume will decrease. This is because the gas molecules are more closely packed together, leading to more collisions and higher energy levels, resulting in an increase in temperature. The decrease in volume is due to the gas molecules being confined to a smaller space.

## 3. Can the volume of a gas change without changing the pressure or temperature?

Yes, the volume of a gas can change without changing the pressure or temperature if the number of moles of gas is altered. This is described by Avogadro's Law, which states that equal volumes of different gases at the same temperature and pressure contain an equal number of molecules.

## 4. How does the Ideal Gas Law relate to real gases?

The Ideal Gas Law is a simplified model that assumes gases behave ideally, meaning there are no intermolecular forces and the gas molecules have no volume. In reality, gas molecules do have volume and interact with each other, which can cause deviations from the Ideal Gas Law at high pressures and low temperatures.

## 5. How can pressure, temperature, and volume be measured in a gas?

Pressure can be measured using a barometer or a manometer, which measure the force exerted by the gas on a surface. Temperature can be measured using a thermometer, and volume can be measured using a graduated cylinder, burette, or other calibrated vessel.

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