1) To identify a diatomic gas (X2), a researcher carried out the following exper
ID: 922251 • Letter: 1
Question
1) To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 5.2-L bulb, then filled it with the gas at 1.60 atm and 27.0 C and weighed it again. The difference in mass was 9.5 g . Identify the gas. Express your answer as a chemical formula.
2) 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)
You have a 5.50 L gas tank and a 4.50 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 115 atm , to what pressure should you fill the acetylene tank to ensure that you run out of each gas at the same time?
Express your answer with the appropriate units.
Explanation / Answer
1. Mass of the gas at 1.60 atm and 27 O C = 9.5 g
Ideal Gas equation : PV = nRT
Therefore, Calculating the number of moles from the equation by using V = 5.2 L and P =1.6 atm and T= 273+27=300K
We get n= .3528
Therefore .3528 weighs 9.5g.
Or, 1 mole weighs = 26.92g
Atomic weight of the Diatomic =13.6g
Therefore the gas is presumely Nitrogen. (N2)
2. Rate of the reaction = 1/2 ( Rate of Transfer of Acetylene gas) = 1/5 ( Rate of Transfer of Oxygen Gas)
PV= nRT
To run out the gases at the same time, we should have, 1/2 ( dnO2/dt)=1/5(dnC2H2/dt)
Or,
1/2 ( PVO2/RT)=1/5 ( PVC2H2/RT)
Or,
5/2 ( PO2VO2)= ( PC2H2VC2H2)
Or,
PC2H2=5/2 ( 115*5.5)/(4.5)= 351.39atm
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