chemistry
posted by Tiffany .
Imagine that you have a 7.00 gas tank and a 3.50 gas tank. You need to fill one tank with oxygen and the other with acetylene to use in conjunction with your welding torch. If you fill the larger tank with oxygen to a pressure of 115 , to what pressure should you fill the acetylene tank to ensure that you run out of each gas at the same time? Assume ideal behavior for all gases.

You don't have any units listed for the 7.00 and 3.50.

Also, no units on the 115 ??pressure.

How many acetylene molecules do you need for each O2 molecule?
2C2H2 + 5O2 > 4CO2 + 2H2O
5 O2 molecules for every 2 2C2H2 molecules
larger tank has O2
let's say it has 5x moles of O2
p v = 5x r t
115 * 7 = 5 x r t
x r t = 115 * 7/(5 )
now the other tank has 2x moles of C2H2
p * 3.5 = 2 x r t
p = (2/3.5) x r t
p = (2/3.5)(115*7)/5 
I assume that whatever the pressure is, it is absolute and not gage.

I assumed 115 is atm and 7.00 and 3.50 are L and came out with 92 also.

124 atm

It's 84 atm

i just sneezed