anonymous one year ago You have 10 lb of CO2 in a 20 ft3 fire extinguisher at 30 o C. Assuming the ideal gas law holds, what will be the gauge pressure (psig) on the tank when full?

1. Rushwr

Use PV=nRT equation P= Pressure in Nm^-2 V= volume in cubic meters ( So we have to convert it ) n= No. of moles R= universal gas constant T= temperature in Kelvin. ( Since we are given it with Celsius We have to convert that ) Since we aren't given with the no. of moles. We can find no. of moles by mass of CO2 divided by molar mass of CO2 But substitute mass of CO2 should be substituted in grams. SO u have to convert it.

2. anonymous

I have used this but my answer is 64.39 psig but the correct answer should be 51.3 psig :( @Rushwr

3. Rushwr

oh wait here the unit we have to use is psig right? ah then we have to convert the temperature to kelvin and Volume to cubic meters only !

4. anonymous

i have converted ft3 to L and i have also used 0.0821 L atm/K mol for R

5. anonymous

|dw:1441548682633:dw|

6. anonymous

P = 4.53 atm (14.22 psig/1atm) = 64.42 psig

7. anonymous

does my solution seem right? :(

8. Rushwr

1lb = 453.592g SO $n = \frac{ 10 * 453.592g }{ 44gmol ^{-1} } = 103.1mol$ $R = 8.314 JK ^{-1}mol ^{-1}$ T = 273 +30 = 303K 1ft^3 = 0.028 m^3 So V= 20 * 0.028m^3 = 0.56m^3

9. Rushwr

then convert it and see !

10. anonymous

P = 463792.04 ?

11. anonymous

@Rushwr

12. Rushwr

That's what I got too I think that's wrong again ! COnvert and see ! I'll check more !

13. anonymous

what unit is P ? atm?

14. Rushwr

nop Nm^-2

15. anonymous

it's 67.27 psig?

16. Rushwr

Yeah that's what I got too !!!!!!!!! Wondering !

17. anonymous

hmm maybe my professor got it wrong i don't know ¯\_(ツ)_/¯ :)). I'll just ask him. Thank you so much for helping me :D

18. Rushwr

Anytym : 0