The reaction of the molecules to produce ethane is C2H4(g) + H2(g) → C2H6(g).
A mechanism for this reaction is shown below:
(The figures show how the ethene molecule with two hydrogen molecules attached 'binds' to nickel. Then four more hydrogen atoms are bound to the nickel, but two of those hydrogen atoms bind to the ethene molecule and then ethane is produced).
Explain the mechanism shown in the figure.
Please help!
google hydrogenation of ethylene to yield ethane on a nickel surface.
What is going on it is not a pure nickel surface, there are molecules of Ni(NiCH) on that surface. As ethylene passes over, there are a series of surface reactions exchanging carbon and hydrogens as bonds are broken and reformed. The total energy required for this series of reaction is lower than the activation energy of the basic reaction, and those pathways then dominate.
Well, it seems like the molecules are having quite the bonding party here. Let me break it down for you.
First, we have our good friend ethene (C2H4), which decides it's time for a change and wants to become ethane (C2H6). So, it goes up to nickel and says, "Hey, buddy! Can you help me out here?" And nickel, being the friendly metal that it is, agrees to lend a hand.
In the first step, ethene binds itself to nickel, kind of like a group hug. This creates a bond between the two, forming a complex. It's like ethene saying, "Nickel, you complete me."
Now comes the fun part. Four hydrogen atoms come along and see this little bonding party happening. They want to join in on the action. Two of the hydrogen atoms decide to bind themselves to the ethene molecule, creating bonds. This is like two hydrogen atoms saying, "Hey ethene, can we crash at your place?"
The other two hydrogen atoms bind themselves to the nickel, kind of like saying, "Hey nickel, we heard this is where the party's at!"
And just like that, magic happens! The ethane molecule is formed, with ethene happily transformed into its new, more stable form. It's like ethene saying, "I’ve upgraded to ethane! Thanks for the help, nickel!"
So, in a nutshell, the mechanism in the figure shows ethene binding to nickel, then hydrogen atoms joining in on the fun to create the beautiful molecule we call ethane. It's a bit like a molecular party, with everyone forming bonds and having a great time.
The mechanism shown in the given figure is a representation of the reaction of ethene (C2H4) with hydrogen (H2) to produce ethane (C2H6) in the presence of a nickel catalyst.
1. The first step involves the adsorption of ethene (C2H4) onto the surface of the nickel catalyst. The ethene molecule binds to the nickel surface, forming weak bonds between the carbon atoms of the ethene molecule and the nickel atoms.
2. Next, hydrogen molecules (H2) approach the surface of the nickel catalyst. One hydrogen molecule binds to the nickel surface, displacing one of the carbon atoms from the ethene molecule. This forms a new Ni-H bond and generates a carbon-centered radical intermediate.
3. In the third step, another hydrogen molecule binds to the carbon-centered radical intermediate, forming a Ni-H bond. This results in the formation of a new ethyl (C2H5) species, still bound to the nickel surface.
4. Finally, a hydrogen atom from the ethyl species transfers to the neighboring carbon atom, resulting in the formation of ethane (C2H6). The ethane molecule is then released from the nickel surface, allowing the catalyst to participate in subsequent cycles of the reaction.
Overall, this mechanism involves the adsorption of ethene onto the nickel catalyst, followed by sequential hydrogenation reactions to form ethane. The nickel catalyst acts as a facilitator, providing a surface for the reactants to interact and promoting the formation of the desired product.
The figure you provided shows the mechanism for the reaction between ethene (C2H4) and hydrogen (H2) to produce ethane (C2H6) using nickel as a catalyst. Let's break down the mechanism step by step to understand what is happening.
Step 1: Ethene binds to nickel
In this step, ethene molecules come in contact with the nickel catalyst surface. The double bond in the ethene molecule "grabs" onto the nickel surface, forming a bond.
Step 2: Hydrogen binds to nickel
In the second step, hydrogen molecules (H2) approach the nickel surface. The nickel catalyst helps break the H-H bond in the hydrogen molecule, allowing each hydrogen atom to bind individually to the nickel surface.
Step 3: Hydrogen binds to ethene
In this step, two of the hydrogen atoms bound to the nickel surface "jump" from the nickel to the ethene molecule, forming bonds with the carbon atoms that were part of the original double bond. This causes the double bond in ethene to break and form single bonds, transforming it into ethane.
Step 4: Ethane detaches from the nickel
Finally, the ethane molecule, now formed due to the hydrogenation of ethene, detaches from the nickel surface, leaving the nickel ready to catalyze more reactions.
It's important to note that the nickel catalyst is not consumed during the reaction. It facilitates the reaction by providing a surface for the reactant molecules to interact, lowering the activation energy required for the reaction to occur. This mechanism allows for the conversion of ethene and hydrogen into ethane.
I hope this explanation helps you understand the mechanism shown in the given figure.