# Chemistry - p1v1/t1 = p2v2/t2???

#1
I really don't get this equation and how to rearrange it. Can somebody help?
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6 years ago
#2
Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

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Just quoting in Puddles the Monkey so she can move the thread if needed
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(Original post by Puddles the Monkey)
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#3
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6 years ago
#4
(Original post by AndrewKn0x)
I really don't get this equation and how to rearrange it. Can somebody help?
I am assuming you are talking about PV = nRT right?

The equation comes from gas laws. Boyle's Law and Charles' Law and the Pressure Law. Basically if you have a ideal gas in one situation and the another situation the three things that can change are Pressure, Volume and Temp. (Fixed mass of gas so mol doesn't change).

Rearranging PV = nRT we get PV/T = nR (nR is a constant because they stay the same).

So in two situations P1 V1 / T1 = nR and P2 V2 / T2 = nR
Since nR is the same in both situations we can equate the two to get your equation:

P1 V1 / T1 = P2 V2 / T2

Example Question: A gas in a box is at 290K. The pressure of a gas is 2.0X105 Pa and the Volume is 1x10-3 m3. The temperature of the box is increased to 390K whilst the Volume remains the same. What is the pressure of the gas now?

P1 = 2.0X105 V1 = 1x10-3 T1 = 290

P2 = ??? V2 = 1x10-3 T2 = 390

2.0x105 x 1x10-3 / 290 = P2 x 1x10-3 / 390

Simplify up we get:

0.6897 = P2 x 2.5641x10-6

Therefore P2 = 0.6897 / 2.5641x10-6 = 2.7x105 Pa

Hope that helps
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#5
(Original post by sirraza97)
i am assuming you are talking about pv = nrt right?

The equation comes from gas laws. Boyle's law and charles' law and the pressure law. Basically if you have a ideal gas in one situation and the another situation the three things that can change are pressure, volume and temp. (fixed mass of gas so mol doesn't change).

Rearranging pv = nrt we get pv/t = nr (nr is a constant because they stay the same).

So in two situations p1 v1 / t1 = nr and p2 v2 / t2 = nr
since nr is the same in both situations we can equate the two to get your equation:

P1 v1 / t1 = p2 v2 / t2

example question: A gas in a box is at 290k. The pressure of a gas is 2.0x105 pa and the volume is 1x10-3 m3. The temperature of the box is increased to 390k whilst the volume remains the same. What is the pressure of the gas now?

P1 = 2.0x105 v1 = 1x10-3 t1 = 290

p2 = ??? V2 = 1x10-3 t2 = 390

2.0x105 x 1x10-3 / 290 = p2 x 1x10-3 / 390

simplify up we get:

0.6897 = p2 x 2.5641x10-6

therefore p2 = 0.6897 / 2.5641x10-6 = 2.7x105 pa

hope that helps
thank you so much
0
6 years ago
#6
(Original post by AndrewKn0x)
thank you so much
No problem man
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