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July 28, 2015

July 28, 2015

Posted by **hanna banana** on Tuesday, May 11, 2010 at 2:08pm.

- Chemistry -
**hanna banana**, Tuesday, May 11, 2010 at 2:09pmi got the answer, 2.37L..and 28.90 mol.. but that doesnt seem right to me, wouldnt it be the other way around?

P1V1/T1= 2.37 L

n=PV/RT= 28.90 mol

or should they be switched?

- Chemistry -
**DrBob222**, Tuesday, May 11, 2010 at 2:18pmI worked the problem and obtained 28.916 mol which rounds to 28.9 to three s.f. but 2.37 L isn't close.

P1V1/T1 = 2.37. That is right; however, that isn't V2.

You must equate 2.37 on the left to P2V2/T2 and plug in standard conditions. As Bob Pursley wrote,

P1V1/T1 = P2V2/T2 and you have solved only half the equation.

- Chemistry -
**hanna banana**, Tuesday, May 11, 2010 at 2:23pm.0820 L?

- Chemistry -
**DrBob222**, Tuesday, May 11, 2010 at 2:26pmno.

Post your work and I'll find what you are doing wrong.

- Chemistry -
**hanna banana**, Tuesday, May 11, 2010 at 2:31pm2.37= 1atm*22.4L/273K

- Chemistry -
**DrBob222**, Tuesday, May 11, 2010 at 2:38pmPray tell, what is the unknown. You have no unknown. In addition, what you have written is not an equality. 22.4/273 certainly isn't = 2.37.

What is the problem asking for? I thought it wanted you to calculate the new volume at the new conditions? It asks, "What is the volume at STP?"

- Chemistry -
**hanna banana**, Tuesday, May 11, 2010 at 2:43pmYes. i dont know why im having such a problem with this.

35atm820.0L/295K= 2.37

and the stp are, 273K, 1 atm, and 22.4 L

- Chemistry -
**DrBob222**, Tuesday, May 11, 2010 at 3:19pmNo. STP conditions are 273 K and 1 atm p. Your problem, I think, is that you have somehow convinced yourself that the volume is 22.4 L since that is the volume of a mole of gas at STP. But you don't have a mole of gas. You have already figured moles at 28.9 or so and you have much more than 1 mole of gas. You must have much more than 22.4 if you have almost 30 moles of gas.

p1 = 35 atm

V1 = 20.0 L

T1 = 273 + 22 = 295

P2 = 1 atm

V2 = unknown, solve for this.

T2 = 273

(35*20.0/295) = (1*V2/273)

Solve for V2.

(35*20.0/295) = (1*V2/273)