Ethylene (CH, CH2) is the starting point for a wide array of industrial chemical

Question

Ethylene (CH, CH2) is the starting point for a wide array of industrial chemical syntheses. For example, worldwide about 8.0x 10 kg of polyethylene are made from ethylene each year, for use in everything from household plumbing to artificial joints. Natural sources of ethylene are entirely inadequate to meet world demand, so ethane (CH3CH3) from natural gas is "cracked" in refineries at high temperature in a kinetically complex reaction that produces ethylene gas 10 and hydrogen gas. Suppose an engineer studying ethane cracking fills a 80.0 L reaction tank with 19.0 atm of ethane gas and raises the temperature to 700. °C. He believes Kp 10. at this temperature. Calculate the percent by mass of ethylene the engineer expects to find in the equilibrium gas mixture. Round your answer to 2 significant digits. Ar Note for advanced students: the engiheer may be mistaken about the correct value of Kp and the mass percent of ethylene you calculate may not be what he actually observes. x10

Explanation / Answer

Answer...

In the industrial production of ethylene by cracking ethane from natural gas temperature and pressure are kept high to effect good yield. The condition chosen for furnace temperature depends upon the product needed. The percentage of Ethylene C2H4 produced will be approximately 19% of the starting mass of ethane at 1000K. The pressure is kept high in order to prevent gas leakage.

The engineer has kept the pressure high intelligently. He has raised the temperature to 700 degree celsius or (700+273)K. This is good in his part. So he can expect the volume of ethylene as 19% of 80L.

=> 19% of 80L = 19x80/100 = 15.2 L at 700 K and 19 atm. pressure.

Now, we shall calculate the mass of ethylene produced.

Here 15.2 L of ethylene is produced at 700K and 19 atm. pressure. We shall convert this volume to volume at STP, standard temp and pressure.

So using the gas equation

P1V1/T1 = P2V2/T2

1xV1/273 = 19x15.2/700

=> V1 = 112.632 L

Molecular mass of C2H4 = 28 mass units

Since 22.4 L at STP is occupied by 28 mass units

So, 112.632 is occupied by 140.79 mass units. Ans.

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