Ideal Gas Laws

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skycracker00
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Ideal Gas Laws

Post by skycracker00 »

Hey guys, I need help with this question. Super confused on it. Here it is:

A balloon is inflated to 4.50 L with Helium, at a particular initial temperature and pressure. (It is tied off.) Now, assume that the temperatures and pressures referred to are always those prevailing inside the balloon.

Then, what would the volume of the balloon be when the pressure is reduced to 1/3 of the initial value and the Kelvin temperature is reduced to 1/2 of the initial value?

:shock: I have a feeling of where to start but what are the values of the initial pressure? That part is throwing me off!

If anyone could help, that would be nice.

Thanks :)
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ChenBeier
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Re: Ideal Gas Laws

Post by ChenBeier »

Do you know the ideal gas law equation pV = nRT
So you solve for V
Change now p to1/3p and T to 1/2T
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Re: Ideal Gas Laws

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Oh wow, that makes sense! Thank you!
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

So, what is your final answer? What is the ratio of temperature to pressure initially and after making adjustments to their values?
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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Re: Ideal Gas Laws

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I got 0.0250 L. But that was incorrect... not sure what I'm doing wrong?
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

Initially, there was 4.5 L volume of Helium gas in the Balloon. So, what is your computed number of mole of Helium gas?
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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Re: Ideal Gas Laws

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4.50 L x 1 mol He / 22.414 L = 0.200767377 mol (not rounded up)
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

So, Plugging all the available values in to the formula PV=NRT, we get the ratio of Kelvin temperature to pressure in Bar as 2.696927647572174. Thereafter the new ratio is \(\frac{X}{2} \times \frac{3}{Y}\rightarrow \frac{3X}{2Y}\) where X=Kelvin Temperature , Y= Pressure in Bar.

What are the next computational workings you made to arrive at the final answer of 0.0250 L volume of Helium Gas?
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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Re: Ideal Gas Laws

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Hmm.. I just inserted all the values into the equation V=nRT/P. I think I made a mistake though because I got a different answer to the one I wrote before. My new answer is 0.02746 L. Still wrong..

By the way, how did you get that equation? How did you come up with that thinking?
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

Question itself states my thinking. Question says one-half of initial value of temperature(X) and one third of initial value of pressure(Y). So ratio becomes \(\frac{\frac{X}{2}}{\frac{Y}{3}}\).Simplifying, we get \(\frac{3X}{2Y}\). That's it.
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Re: Ideal Gas Laws

Post by ChenBeier »

The result is 1.5 x V.
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

That's correct. thanks. If, i am not wrong, the final volume is 4.04 L of Helium gas in the balloon.
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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Re: Ideal Gas Laws

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You guys have been a real help! Thank you :D
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Re: Ideal Gas Laws

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Its wrong. The result is 6.75 l
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Re: Ideal Gas Laws

Post by Dhamnekar Winod »

Oh, Yes. You are correct. 4.04539 is the new ratio of Kelvin temperature to pressure after making adjustments to their initial values. Thanks for pointing out my mistake.
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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