Question

± Gas Law Stoichiometry

Acetylene torches are used for welding. These torches use a mixture of acetylene gas, C2H2, and oxygen gas, O2 to produce the following combustion reaction:

2C2H2(g)+5O2(g)→4CO2(g)+2H2O(g)

Part A

Imagine that you have a 5.50 L gas tank and a 2.50 L 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 145 atm , 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.

Express your answer with the appropriate units.

Hints

P =

SubmitMy AnswersGive Up

Answer 1

Use conservation theory...

Assume SAME temperature in both cases

so

P*V = constant

we need 2 mol of C2H2 and 5 mol of O2

if we have --> P = 145 atm of Oxygen, V = 5.5 L

PV of oxygen = 145*5.5 = 797.5 atm*L

now,

PV of C2H2 must be kept

ratio is 2:5 so

5/2 is the ratio

5/2*(PV value of C2H2) = PV value of O2

5/2*(PV value of C2H2) = 797.5 atm*L

PV value of C2H2 =  2/5*797.5 atm*L

PV value of C2H2 =319 atm*L

now,

V = 2.5 L will be used, so P of C2H2:

P value of C2H2 =319 atm*L / 2.5 L

P value of C2H2 = (127.6) atm

we will need to use approx 127.6 atm in order to satify this