What is the temperature of the freezer based on the Ideal Gas Law?

In summary: Using 9 as the diameter I was able to get -55 C as an answer. Does that sound right to you? Thank you for your help.
  • #1
Bgerst103
32
0

Homework Statement



Here is the problem: You are worried that your -80C freezer is on the fritz. Unfortunately you do not have a thermometer. You do have a balloon. so, you blow up the balloon and measure that it has a diameter of 10cm when at 25C. you put it in the freezer, let it come to thermal equilibrium, and measure the new volume to be 9cm. What is the temperature of the freezer? (assume the balloon is a perfect sphere).

A) -55C
B) -66C
C) -77C
D) -88C

Homework Equations



I'm really not sure how do solve this with the given information. I am also unsure if the "new volume" is a typo and is actually supposed to be new diameter since the cm are not cubed.

The Attempt at a Solution



I've tried putting numbers in the equation P1V1/T1=P2V2/T2 but never been able to come out with any of those answers.
 
Physics news on Phys.org
  • #2
Bgerst103 said:

Homework Statement



Here is the problem: You are worried that your -80C freezer is on the fritz. Unfortunately you do not have a thermometer. You do have a balloon. so, you blow up the balloon and measure that it has a diameter of 10cm when at 25C. you put it in the freezer, let it come to thermal equilibrium, and measure the new volume to be 9cm. What is the temperature of the freezer? (assume the balloon is a perfect sphere).

A) -55C
B) -66C
C) -77C
D) -88C

Homework Equations



I'm really not sure how do solve this with the given information. I am also unsure if the "new volume" is a typo and is actually supposed to be new diameter since the cm are not cubed.

The Attempt at a Solution



I've tried putting numbers in the equation P1V1/T1=P2V2/T2 but never been able to come out with any of those answers.
Did you remember to use absolute temperature? As far as the diameter issue is concerned, try it both ways and see if you match any of the answers.

Chet
 
  • #3
Chestermiller said:
Did you remember to use absolute temperature? As far as the diameter issue is concerned, try it both ways and see if you match any of the answers.

Chet

What about the pressure calculation? It seems like there are too many variables missing to solve P1V1/T1=P2V2/T2. Is there a way to calculate the pressure of the balloon before it is in the freezer? I know the equation PV=nRT but n is unknown as well. Also, even if P1 can be calculated that still leaves two variables left. We did examples in lecture where only one variable was missing which is why this problem is more confusing. Am I missing some conceptual understanding of the problem where pressure isn't need or can be canceled out?
 
  • #4
Bgerst103 said:
What about the pressure calculation? It seems like there are too many variables missing to solve P1V1/T1=P2V2/T2. Is there a way to calculate the pressure of the balloon before it is in the freezer? I know the equation PV=nRT but n is unknown as well. Also, even if P1 can be calculated that still leaves two variables left. We did examples in lecture where only one variable was missing which is why this problem is more confusing. Am I missing some conceptual understanding of the problem where pressure isn't need or can be canceled out?
The pressure is assumed to stay constant at 1 atm.

Chet
 
  • #5
What are the assumptions behind the ideal gas approximation? Does it matter whether the gas is air, N2, CO2 , He etc.?
 
  • #6
FermiAged said:
What are the assumptions behind the ideal gas approximation?
The pressure is low enough.
Does it matter whether the gas is air, N2, CO2 , He etc.?
No. Only the range of applicability.

Chet
 
  • #7
Chestermiller said:
Did you remember to use absolute temperature? As far as the diameter issue is concerned, try it both ways and see if you match any of the answers.

Chet

Using 9 as the diameter I was able to get -55 C as an answer. Does that sound right to you? Thank you for your help.
 
  • #8
Bgerst103 said:
Using 9 as the diameter I was able to get -55 C as an answer. Does that sound right to you? Thank you for your help.
I get -56 C, but who's counting.

Chet
 

What is the Ideal Gas Law Volume Problem?

The Ideal Gas Law Volume Problem is a mathematical formula used in thermodynamics and chemistry to calculate the volume of a gas at a given temperature, pressure, and number of moles.

What is the ideal gas law equation?

The ideal gas law equation is PV = nRT, where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the ideal gas constant, and T is the temperature of the gas.

What is the ideal gas constant?

The ideal gas constant, denoted by the symbol R, is a physical constant that relates the energy of a gas to its temperature, pressure, and volume. Its value is approximately 8.314 J/mol·K.

How do you use the Ideal Gas Law Volume Problem to solve for volume?

To solve for volume, you would rearrange the ideal gas law equation to V = nRT/P. Then, plug in the values for pressure, number of moles, ideal gas constant, and temperature to calculate the volume of the gas.

What are the units for the variables in the Ideal Gas Law Volume Problem?

The units for pressure (P) are usually in atmospheres (atm) or kilopascals (kPa), volume (V) is typically in liters (L) or cubic meters (m^3), number of moles (n) is in moles (mol), ideal gas constant (R) is in joules per mole-kelvin (J/mol·K), and temperature (T) is in kelvin (K).

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
442
  • Introductory Physics Homework Help
Replies
3
Views
8K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
607
  • Introductory Physics Homework Help
Replies
24
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
3K
  • Introductory Physics Homework Help
Replies
5
Views
966
Replies
2
Views
989
  • Introductory Physics Homework Help
Replies
21
Views
2K
  • Introductory Physics Homework Help
Replies
9
Views
1K
Back
Top