Thermal Processes: Ideal Gas Expansion with Constant Pressure [SOLVED]

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In summary, the gas expanded from 0.75 meters cubed to 2.0 meters cubed, and did work of 3.0*10^5 Joules. The gas reached initial and final temperatures of 273K and 373K, respectively, and the internal energy of the gas increased by 20.775 Joules. Heat was added to the system, causing the temperature to increase by 4.2K.
  • #1
HELLO11
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[SOLVED] Thermal Processes

Homework Statement



With the pressure held constant at 240 kPa , 42 mol of a monatomic ideal gas expands from an initial volume of 0.75 meters cubed to a final volume of 2.0 meters cubed.

a)How much work is done by the gas during expansion?
b)What were the initial and final temperatures?
c)what was the change in the internal energy of the gas?
d)How much heat was added?

I know the anwser for a) is 3.0*10^5
i can't find the other three

can someone please help
 
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  • #2
HELLO11 said:
i can't find the other three

Where have you looked?
 
  • #3
HELLO11 said:

Homework Statement



With the pressure held constant at 240 kPa , 42 mol of a monatomic ideal gas expands from an initial volume of 0.75 meters cubed to a final volume of 2.0 meters cubed.

a)How much work is done by the gas during expansion?
b)What were the initial and final temperatures?
Use ideal gas law: PV = nRT. You know P, V and n so just work out T for intial and final states.
c)what was the change in the internal energy of the gas?
What is Cv for a monatomic gas? How is [itex]\Delta U[/itex] related to Cv and [itex]\Delta T[/itex]?
d)How much heat was added?
Use first law: dQ = dU + dW

As a short-cut, since it is a constant pressure process, you can just use: dQ = CpdT. What is Cp for a monatomic gas?

I know the anwser for a) is 3.0*10^5

Units?

AM
 
  • #4
the units for the first answer are Joules

How do i wotk out the T for inital and final states
 
  • #5
the Cv for a monatomic gas is 12.465

delta U is 3/2*n*R*deltaT
 
  • #6
Cp for a monatomic gas is 20.775
 
  • #7
HELLO11 said:
the units for the first answer are Joules

How do i wotk out the T for inital and final states

Use the ideal gas law PV=nRT like Andrew suggested in post #3. You were given all the information you need to solve this for T.
 
  • #8
For T i get 859.5 How do i get the inital temperature
 
  • #9
You just use the ideal gas law twice. Once for the initial state (so before it expands), and once for the final state (after it expands).

Be very careful with your units.
 
  • #10
thanks for all your help
 

1. What is a thermal process?

A thermal process is any process that involves the transfer of heat energy from one system to another. This can include heating, cooling, or maintaining a constant temperature.

2. What are some common examples of thermal processes?

Some common examples of thermal processes include cooking food, melting ice, boiling water, and using a hairdryer.

3. How do thermal processes affect materials?

Thermal processes can affect materials in different ways, depending on the type of material and the temperature it is exposed to. For example, heating a metal can cause it to expand, while cooling it can cause it to contract.

4. What is the difference between conduction, convection, and radiation in thermal processes?

Conduction is the transfer of heat energy through direct contact between two objects. Convection is the transfer of heat through the movement of fluids, such as air or water. Radiation is the transfer of heat through electromagnetic waves.

5. How do thermal processes play a role in everyday life?

Thermal processes are an essential part of everyday life, from cooking and heating our homes to powering our vehicles and devices. They also play a crucial role in many industrial processes, such as manufacturing and power generation.

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