Physics: Expansion at constant pressure

In summary, an unknown number of moles of an ideal monoatomic gas expand reversibly from Vi = 2.30 m3 to Vf = 3.10 m3, at a constant pressure of 1.71 atm and an initial temperature of 300 K. To find the number of moles of gas, the equation PV=nRT is used. Converting the pressure in atm to N/m^2 and keeping the initial volume as V, 8.315 for R and the initial temperature in K, the result is the same but incorrect. The method of using the equation of state for the initial state is appropriate, but it is important to not convert m^3 to liters.
  • #1
FutureE'neer
3
0
An unknown number of moles of an ideal monoatomic gas expand reversibly from Vi = 2.30 m3 to Vf = 3.10 m3, at a constant pressure of 1.71 atm and an initial temperature of 300 K.
Find the number of moles of gas.
Find the final temperature of the gas K.
Calculate the work done by the gas.

I cannot find the number of moles and I don't know what I'm doing wrong.
I'm using PV=nRT
Converting the pressure in atm to N/m^2 and m^3 to L. I'm using the initial volume for V, 8.315 for R and the initial temp in K and solving for n. I keep getting the same answer and it is coming up wrong. Please help!
 
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  • #2
Keywords are "ideal monoatomic gas expand reversibly "
What does that mean to you?
 
  • #3
that's how much it fluctuate's?
 
  • #4
FutureE'neer said:
I cannot find the number of moles and I don't know what I'm doing wrong.
I'm using PV=nRT
Converting the pressure in atm to N/m^2 and m^3 to L. I'm using the initial volume for V, 8.315 for R and the initial temp in K and solving for n. I keep getting the same answer and it is coming up wrong. Please help!
Can you show what you did (and how do you know is wrong)?
The method (using equation of state for initial state) seems OK.
 
  • #5
Don't change m^3 to litres
 

1. What is the definition of expansion at constant pressure in physics?

In physics, expansion at constant pressure refers to the process in which a substance expands or increases in volume while its pressure remains constant. This means that the external pressure applied to the substance remains the same throughout the expansion process.

2. What causes expansion at constant pressure?

The main cause of expansion at constant pressure is the increase in temperature of a substance. As the temperature of a substance increases, its particles gain more energy and move faster, causing them to spread out and take up more space, resulting in an expansion of the substance.

3. What is the equation for calculating expansion at constant pressure?

The equation for calculating expansion at constant pressure is ΔV = V₀αΔT, where ΔV is the change in volume, V₀ is the initial volume, α is the coefficient of thermal expansion, and ΔT is the change in temperature.

4. How does expansion at constant pressure differ from expansion at constant volume?

Expansion at constant pressure differs from expansion at constant volume in that during constant pressure expansion, the external pressure remains the same while the volume of the substance increases. In contrast, during constant volume expansion, the volume remains the same while the pressure of the substance increases.

5. What are some real-life examples of expansion at constant pressure?

Some real-life examples of expansion at constant pressure include the expansion of air inside a balloon when it is placed in a warm room, the increase in volume of a liquid in a thermometer when it is exposed to a higher temperature, and the expansion of metals in bridges and buildings on a hot day.

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